256639172 has 24 divisors (see below), whose sum is σ = 461938680. Its totient is φ = 124682240.

The previous prime is 256639171. The next prime is 256639177. The reversal of 256639172 is 271936652.

It can be written as a sum of positive squares in 4 ways, for example, as 21752896 + 234886276 = 4664^2 + 15326^2 .

It is a Harshad number since it is a multiple of its sum of digits (41).

It is not an unprimeable number, because it can be changed into a prime (256639171) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 39104 + ... + 45192.

It is an arithmetic number, because the mean of its divisors is an integer number (19247445).

Almost surely, 2^256639172 is an apocalyptic number.

It is an amenable number.

256639172 is a deficient number, since it is larger than the sum of its proper divisors (205299508).

256639172 is a wasteful number, since it uses less digits than its factorization.

256639172 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6391 (or 6389 counting only the distinct ones).

The product of its digits is 136080, while the sum is 41.

The square root of 256639172 is about 16019.9616728630. The cubic root of 256639172 is about 635.4884307091.

The spelling of 256639172 in words is "two hundred fifty-six million, six hundred thirty-nine thousand, one hundred seventy-two".