256521125646 has 12 divisors (see below), whose sum is σ = 555795772272. Its totient is φ = 85507041876.

The previous prime is 256521125617. The next prime is 256521125647. The reversal of 256521125646 is 646521125652.

256521125646 is a `hidden beast` number, since 2 + 5 + 65 + 21 + 1 + 2 + 564 + 6 = 666.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (256521125647) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 7125586806 + ... + 7125586841.

It is an arithmetic number, because the mean of its divisors is an integer number (46316314356).

Almost surely, 2^256521125646 is an apocalyptic number.

256521125646 is an abundant number, since it is smaller than the sum of its proper divisors (299274646626).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

256521125646 is a wasteful number, since it uses less digits than its factorization.

256521125646 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 14251173655 (or 14251173652 counting only the distinct ones).

The product of its digits is 864000, while the sum is 45.

The spelling of 256521125646 in words is "two hundred fifty-six billion, five hundred twenty-one million, one hundred twenty-five thousand, six hundred forty-six".