# 290 (number)

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Cardinal two hundred ninety
Ordinal 290th
(two hundred and ninetieth)
Factorization 2 × 5 × 29
Roman numeral CCXC
Binary 1001000102
Ternary 1012023
Quaternary 102024
Quinary 21305
Senary 12026
Octal 4428
Duodecimal 20212
Vigesimal EA20
Base 36 8236

290 (two hundred [and] ninety) is the natural number after 289 and before 291.

## In mathematics

The product of three primes, 290 is a sphenic number, and the sum of four consecutive primes (67 + 71 + 73 + 79). The sum of the squares of the divisors of 17 is 290. If you multiply 5, 2, and 29, you get 290.

Not only is it a nontotient and a noncototient, it is also an untouchable number.

290 is the 16th member of the Mian–Chowla sequence; it can not be obtained as the sum of any two previous terms in the sequence.[1]

## 291 to 299

### 291

Two hundred [and] ninety-one 291 = 3·97, a semiprime.

### 292

Two hundred [and] ninety-two 292 = 22·73, noncototient, untouchable number. The continued fraction representation of pi is [3; 7, 15, 1, 292, 1, 1, 1, 2...]; the convergent obtained by truncating before the surprisingly large term 292 yields the excellent rational approximation 355/113 to pi, repdigit in base 8 (444).

### 293

Two hundred [and] ninety-three 293 prime, Sophie Germain prime, Chen prime, Irregular prime, Eisenstein prime with no imaginary part, strictly non-palindromic number. For 293 cells in cell biology, see HEK cell.

### 295

Two hundred [and] ninety-five 295 = 5·59, also, the numerical designation of seven circumfrental or half-circumfrental routes of Interstate 95 in the United States.

### 296

Two hundred [and] ninety-six 296 = 23·37, unique period in base 2

### 297

Two hundred [and] ninety-seven 297 = 33·11, number of integer partitions of 17, decagonal number, Kaprekar number

### 298

Two hundred [and] ninety-eight 298 = 2·149, nontotient, noncototient

### 299

Two hundred [and] ninety-nine 299 = 13·23, highly cototient number, self number, the twelfth cake number

## References

1. "Sloane's A005282 : Mian-Chowla sequence". The On-Line Encyclopedia of Integer Sequences. OEIS Foundation. Retrieved 2016-05-28.<templatestyles src="Module:Citation/CS1/styles.css"></templatestyles>