256520137 has 2 divisors, whose sum is σ = 256520138. Its totient is φ = 256520136.

The previous prime is 256520129. The next prime is 256520171. The reversal of 256520137 is 731025652.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 164762896 + 91757241 = 12836^2 + 9579^2 .

It is a cyclic number.

It is not a de Polignac number, because 256520137 - 2³ = 256520129 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 256520099 and 256520108.

It is not a weakly prime, because it can be changed into another prime (256520107) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128260068 + 128260069.

It is an arithmetic number, because the mean of its divisors is an integer number (128260069).

Almost surely, 2^256520137 is an apocalyptic number.

It is an amenable number.

256520137 is a deficient number, since it is larger than the sum of its proper divisors (1).

256520137 is an equidigital number, since it uses as much as digits as its factorization.

256520137 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 12600, while the sum is 31.

The square root of 256520137 is about 16016.2460333250. The cubic root of 256520137 is about 635.3901642557.

Adding to 256520137 its reverse (731025652), we get a palindrome (987545789).

The spelling of 256520137 in words is "two hundred fifty-six million, five hundred twenty thousand, one hundred thirty-seven".