256172291 has 2 divisors, whose sum is σ = 256172292. Its totient is φ = 256172290.

The previous prime is 256172261. The next prime is 256172309. The reversal of 256172291 is 192271652.

It is a strong prime.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-256172291 is a prime.

It is a super-3 number, since 3×256172291³ (a number of 26 digits) contains 333 as substring.

It is a Sophie Germain prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (256172221) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128086145 + 128086146.

It is an arithmetic number, because the mean of its divisors is an integer number (128086146).

Almost surely, 2^256172291 is an apocalyptic number.

256172291 is a deficient number, since it is larger than the sum of its proper divisors (1).

256172291 is an equidigital number, since it uses as much as digits as its factorization.

256172291 is an evil number, because the sum of its binary digits is even.

The product of its digits is 15120, while the sum is 35.

The square root of 256172291 is about 16005.3831881652. The cubic root of 256172291 is about 635.1028341115.

The spelling of 256172291 in words is "two hundred fifty-six million, one hundred seventy-two thousand, two hundred ninety-one".