639707720 has 16 divisors (see below), whose sum is σ = 1439342460. Its totient is φ = 255883072.

The previous prime is 639707701. The next prime is 639707729. The reversal of 639707720 is 27707936.

It can be written as a sum of positive squares in 2 ways, for example, as 634334596 + 5373124 = 25186^2 + 2318^2 .

It is not an unprimeable number, because it can be changed into a prime (639707729) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7996307 + ... + 7996386.

Almost surely, 2^639707720 is an apocalyptic number.

It is an amenable number.

639707720 is an abundant number, since it is smaller than the sum of its proper divisors (799634740).

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

639707720 is a wasteful number, since it uses less digits than its factorization.

639707720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15992704 (or 15992700 counting only the distinct ones).

The product of its (nonzero) digits is 111132, while the sum is 41.

The square root of 639707720 is about 25292.4439309451. The cubic root of 639707720 is about 861.6426689182.

The spelling of 639707720 in words is "six hundred thirty-nine million, seven hundred seven thousand, seven hundred twenty".