639491402 has 16 divisors (see below), whose sum is σ = 1091938752. Its totient is φ = 278039520.

The previous prime is 639491351. The next prime is 639491443. The reversal of 639491402 is 204194936.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 631403 + ... + 632414.

It is an arithmetic number, because the mean of its divisors is an integer number (68246172).

Almost surely, 2^639491402 is an apocalyptic number.

639491402 is a deficient number, since it is larger than the sum of its proper divisors (452447350).

639491402 is a wasteful number, since it uses less digits than its factorization.

639491402 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1263853.

The product of its (nonzero) digits is 46656, while the sum is 38.

The square root of 639491402 is about 25288.1672329175. The cubic root of 639491402 is about 861.5455361047.

The spelling of 639491402 in words is "six hundred thirty-nine million, four hundred ninety-one thousand, four hundred two".