639655212 has 90 divisors (see below), whose sum is σ = 1752944228. Its totient is φ = 181532064.

The previous prime is 639655171. The next prime is 639655241. The reversal of 639655212 is 212556936.

It is an unprimeable number.

It is a polite number, since it can be written in 29 ways as a sum of consecutive naturals, for example, 4292914 + ... + 4293062.

Almost surely, 2^639655212 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 639655212, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (876472114).

639655212 is an abundant number, since it is smaller than the sum of its proper divisors (1113289016).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

639655212 is an equidigital number, since it uses as much as digits as its factorization.

639655212 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 333 (or 161 counting only the distinct ones).

The product of its digits is 97200, while the sum is 39.

The square root of 639655212 is about 25291.4058921207. The cubic root of 639655212 is about 861.6190933749.

Multiplying 639655212 by its product of digits (97200), we get a square (62174486606400 = 7885080²).

The spelling of 639655212 in words is "six hundred thirty-nine million, six hundred fifty-five thousand, two hundred twelve".