256731508705 has 24 divisors (see below), whose sum is σ = 370734039720. Its totient is φ = 169973959680.

The previous prime is 256731508697. The next prime is 256731508727. The reversal of 256731508705 is 507805137652.

It can be written as a sum of positive squares in 4 ways, for example, as 785568784 + 255945939921 = 28028^2 + 505911^2 .

It is not a de Polignac number, because 256731508705 - 2³ = 256731508697 is a prime.

It is a super-2 number, since 2×256731508705² (a number of 24 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (49).

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 18059856 + ... + 18074065.

It is an arithmetic number, because the mean of its divisors is an integer number (15447251655).

Almost surely, 2^256731508705 is an apocalyptic number.

It is an amenable number.

256731508705 is a deficient number, since it is larger than the sum of its proper divisors (114002531015).

256731508705 is a wasteful number, since it uses less digits than its factorization.

256731508705 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 36133969 (or 36133962 counting only the distinct ones).

The product of its (nonzero) digits is 1764000, while the sum is 49.

The spelling of 256731508705 in words is "two hundred fifty-six billion, seven hundred thirty-one million, five hundred eight thousand, seven hundred five".