256420021504 has 36 divisors (see below), whose sum is σ = 512817328576. Its totient is φ = 127964800512.

The previous prime is 256420021471. The next prime is 256420021511. The reversal of 256420021504 is 405120024652.

It is a super-2 number, since 2×256420021504² (a number of 24 digits) contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 823704 + ... + 1091479.

Almost surely, 2^256420021504 is an apocalyptic number.

It is an amenable number.

256420021504 is a deficient number, since it is larger than the sum of its proper divisors (256397307072).

256420021504 is an equidigital number, since it uses as much as digits as its factorization.

256420021504 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1915722 (or 1915708 counting only the distinct ones).

The product of its (nonzero) digits is 19200, while the sum is 31.

The spelling of 256420021504 in words is "two hundred fifty-six billion, four hundred twenty million, twenty-one thousand, five hundred four".