639906506 has 8 divisors (see below), whose sum is σ = 1001592864. Its totient is φ = 306042220.

The previous prime is 639906499. The next prime is 639906523. The reversal of 639906506 is 605609936.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×639906506² = 818960672842256072, which contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6955460 + ... + 6955551.

It is an arithmetic number, because the mean of its divisors is an integer number (125199108).

Almost surely, 2^639906506 is an apocalyptic number.

639906506 is a deficient number, since it is larger than the sum of its proper divisors (361686358).

639906506 is a wasteful number, since it uses less digits than its factorization.

639906506 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13911036.

The product of its (nonzero) digits is 262440, while the sum is 44.

The square root of 639906506 is about 25296.3733764348. The cubic root of 639906506 is about 861.7319100698.

The spelling of 639906506 in words is "six hundred thirty-nine million, nine hundred six thousand, five hundred six".