256136213521 has 16 divisors (see below), whose sum is σ = 258437612160. Its totient is φ = 253847502720.

The previous prime is 256136213503. The next prime is 256136213527. The reversal of 256136213521 is 125312631652.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-256136213521 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (256136213527) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 62884341 + ... + 62888413.

It is an arithmetic number, because the mean of its divisors is an integer number (16152350760).

Almost surely, 2^256136213521 is an apocalyptic number.

It is an amenable number.

256136213521 is a deficient number, since it is larger than the sum of its proper divisors (2301398639).

256136213521 is a wasteful number, since it uses less digits than its factorization.

256136213521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5496.

The product of its digits is 64800, while the sum is 37.

The spelling of 256136213521 in words is "two hundred fifty-six billion, one hundred thirty-six million, two hundred thirteen thousand, five hundred twenty-one".