256121605237 has 2 divisors, whose sum is σ = 256121605238. Its totient is φ = 256121605236.

The previous prime is 256121605211. The next prime is 256121605247. The reversal of 256121605237 is 732506121652.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 141887069041 + 114234536196 = 376679^2 + 337986^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-256121605237 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 256121605237.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (256121605247) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 128060802618 + 128060802619.

It is an arithmetic number, because the mean of its divisors is an integer number (128060802619).

Almost surely, 2^256121605237 is an apocalyptic number.

It is an amenable number.

256121605237 is a deficient number, since it is larger than the sum of its proper divisors (1).

256121605237 is an equidigital number, since it uses as much as digits as its factorization.

256121605237 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 151200, while the sum is 40.

Adding to 256121605237 its reverse (732506121652), we get a palindrome (988627726889).

The spelling of 256121605237 in words is "two hundred fifty-six billion, one hundred twenty-one million, six hundred five thousand, two hundred thirty-seven".