639531225 has 18 divisors (see below), whose sum is σ = 1145471886. Its totient is φ = 341083200.

The previous prime is 639531197. The next prime is 639531227. The reversal of 639531225 is 522135936.

639531225 is a `hidden beast` number, since 639 + 5 + 3 + 12 + 2 + 5 = 666.

It can be written as a sum of positive squares in 3 ways, for example, as 210047049 + 429484176 = 14493^2 + 20724^2 .

It is not a de Polignac number, because 639531225 - 2⁷ = 639531097 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 639531225.

It is not an unprimeable number, because it can be changed into a prime (639531227) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 1420956 + ... + 1421405.

It is an arithmetic number, because the mean of its divisors is an integer number (63637327).

Almost surely, 2^639531225 is an apocalyptic number.

It is an amenable number.

639531225 is a deficient number, since it is larger than the sum of its proper divisors (505940661).

639531225 is a wasteful number, since it uses less digits than its factorization.

639531225 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2842377 (or 2842369 counting only the distinct ones).

The product of its digits is 48600, while the sum is 36.

The square root of 639531225 is about 25288.9546047281. The cubic root of 639531225 is about 861.5634193869.

The spelling of 639531225 in words is "six hundred thirty-nine million, five hundred thirty-one thousand, two hundred twenty-five".