256515921090 has 384 divisors, whose sum is σ = 815087669760. Its totient is φ = 57021719040.

The previous prime is 256515921049. The next prime is 256515921119. The reversal of 256515921090 is 90129515652.

256515921090 is a `hidden beast` number, since 2 + 5 + 6 + 51 + 592 + 1 + 0 + 9 + 0 = 666.

256515921090 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×256515921090² (a number of 24 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 191 ways as a sum of consecutive naturals, for example, 66677547 + ... + 66681393.

It is an arithmetic number, because the mean of its divisors is an integer number (2122624140).

Almost surely, 2^256515921090 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 256515921090, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (407543834880).

256515921090 is an abundant number, since it is smaller than the sum of its proper divisors (558571748670).

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

256515921090 is a wasteful number, since it uses less digits than its factorization.

256515921090 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4055 (or 4038 counting only the distinct ones).

The product of its (nonzero) digits is 243000, while the sum is 45.

The spelling of 256515921090 in words is "two hundred fifty-six billion, five hundred fifteen million, nine hundred twenty-one thousand, ninety".