639936680 has 16 divisors (see below), whose sum is σ = 1439857620. Its totient is φ = 255974656.

The previous prime is 639936677. The next prime is 639936683. The reversal of 639936680 is 86639936.

It is an interprime number because it is at equal distance from previous prime (639936677) and next prime (639936683).

It can be written as a sum of positive squares in 2 ways, for example, as 582449956 + 57486724 = 24134^2 + 7582^2 .

It is not an unprimeable number, because it can be changed into a prime (639936683) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7999169 + ... + 7999248.

Almost surely, 2^639936680 is an apocalyptic number.

It is an amenable number.

639936680 is an abundant number, since it is smaller than the sum of its proper divisors (799920940).

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

639936680 is a wasteful number, since it uses less digits than its factorization.

639936680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15998428 (or 15998424 counting only the distinct ones).

The product of its (nonzero) digits is 1259712, while the sum is 50.

The square root of 639936680 is about 25296.9697790071. The cubic root of 639936680 is about 861.7454544911.

The spelling of 639936680 in words is "six hundred thirty-nine million, nine hundred thirty-six thousand, six hundred eighty".