639005906 has 16 divisors (see below), whose sum is σ = 1195024320. Its totient is φ = 248963280.

The previous prime is 639005903. The next prime is 639005953. The reversal of 639005906 is 609500936.

It is a self number, because there is not a number n which added to its sum of digits gives 639005906.

It is not an unprimeable number, because it can be changed into a prime (639005903) 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, 2074541 + ... + 2074848.

It is an arithmetic number, because the mean of its divisors is an integer number (74689020).

Almost surely, 2^639005906 is an apocalyptic number.

639005906 is a deficient number, since it is larger than the sum of its proper divisors (556018414).

639005906 is a wasteful number, since it uses less digits than its factorization.

639005906 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4149409.

The product of its (nonzero) digits is 43740, while the sum is 38.

The square root of 639005906 is about 25278.5661381337. The cubic root of 639005906 is about 861.3274550871.

The spelling of 639005906 in words is "six hundred thirty-nine million, five thousand, nine hundred six".