256724751525521 has 4 divisors (see below), whose sum is σ = 270236580553200. Its totient is φ = 243212922497844.

The previous prime is 256724751525511. The next prime is 256724751525527. The reversal of 256724751525521 is 125525157427652.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 256724751525521 - 2⁴⁶ = 186356007347857 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (256724751525527) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6755914513811 + ... + 6755914513848.

It is an arithmetic number, because the mean of its divisors is an integer number (67559145138300).

Almost surely, 2^{256724751525521} is an apocalyptic number.

It is an amenable number.

256724751525521 is a deficient number, since it is larger than the sum of its proper divisors (13511829027679).

256724751525521 is a wasteful number, since it uses less digits than its factorization.

256724751525521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13511829027678.

The product of its digits is 58800000, while the sum is 59.

The spelling of 256724751525521 in words is "two hundred fifty-six trillion, seven hundred twenty-four billion, seven hundred fifty-one million, five hundred twenty-five thousand, five hundred twenty-one".