639682905 has 32 divisors (see below), whose sum is σ = 1046897280. Its totient is φ = 333434880.

The previous prime is 639682903. The next prime is 639682933. The reversal of 639682905 is 509286936.

It is not a de Polignac number, because 639682905 - 2¹ = 639682903 is a prime.

It is a Smith number, since the sum of its digits (48) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is not an unprimeable number, because it can be changed into a prime (639682903) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 147001 + ... + 151289.

It is an arithmetic number, because the mean of its divisors is an integer number (32715540).

Almost surely, 2^639682905 is an apocalyptic number.

It is an amenable number.

639682905 is a deficient number, since it is larger than the sum of its proper divisors (407214375).

639682905 is a wasteful number, since it uses less digits than its factorization.

639682905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4521.

The product of its (nonzero) digits is 699840, while the sum is 48.

The square root of 639682905 is about 25291.9533646573. The cubic root of 639682905 is about 861.6315274033.

The spelling of 639682905 in words is "six hundred thirty-nine million, six hundred eighty-two thousand, nine hundred five".