256307212121 has 8 divisors (see below), whose sum is σ = 261241154664. Its totient is φ = 251420037120.

The previous prime is 256307212103. The next prime is 256307212157. The reversal of 256307212121 is 121212703652.

It can be written as a sum of positive squares in 4 ways, for example, as 19547115721 + 236760096400 = 139811^2 + 486580^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-256307212121 is a prime.

It is an alternating number because its digits alternate between even and odd.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (256307212621) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11680820 + ... + 11702741.

It is an arithmetic number, because the mean of its divisors is an integer number (32655144333).

Almost surely, 2^256307212121 is an apocalyptic number.

It is an amenable number.

256307212121 is a deficient number, since it is larger than the sum of its proper divisors (4933942543).

256307212121 is a wasteful number, since it uses less digits than its factorization.

256307212121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23383771.

The product of its (nonzero) digits is 10080, while the sum is 32.

Adding to 256307212121 its reverse (121212703652), we get a palindrome (377519915773).

The spelling of 256307212121 in words is "two hundred fifty-six billion, three hundred seven million, two hundred twelve thousand, one hundred twenty-one".