639213896 has 8 divisors (see below), whose sum is σ = 1198526070. Its totient is φ = 319606944.

The previous prime is 639213863. The next prime is 639213901. The reversal of 639213896 is 698312936.

It can be written as a sum of positive squares in only one way, i.e., 565012900 + 74200996 = 23770^2 + 8614^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is a self number, because there is not a number n which added to its sum of digits gives 639213896.

It is an unprimeable number.

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 as a sum of consecutive naturals, namely, 39950861 + ... + 39950876.

Almost surely, 2^639213896 is an apocalyptic number.

It is an amenable number.

639213896 is a deficient number, since it is larger than the sum of its proper divisors (559312174).

639213896 is a wasteful number, since it uses less digits than its factorization.

639213896 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79901743 (or 79901739 counting only the distinct ones).

The product of its digits is 419904, while the sum is 47.

The square root of 639213896 is about 25282.6797630314. The cubic root of 639213896 is about 861.4208960931.

The spelling of 639213896 in words is "six hundred thirty-nine million, two hundred thirteen thousand, eight hundred ninety-six".