639987903 has 36 divisors (see below), whose sum is σ = 972240360. Its totient is φ = 405633888.

The previous prime is 639987893. The next prime is 639987937. The reversal of 639987903 is 309789936.

It is not a de Polignac number, because 639987903 - 2¹² = 639983807 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 639987903.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639987973) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 1089976 + ... + 1090562.

Almost surely, 2^639987903 is an apocalyptic number.

639987903 is a deficient number, since it is larger than the sum of its proper divisors (332252457).

639987903 is a wasteful number, since it uses less digits than its factorization.

639987903 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 868 (or 842 counting only the distinct ones).

The product of its (nonzero) digits is 2204496, while the sum is 54.

The square root of 639987903 is about 25297.9821922619. The cubic root of 639987903 is about 861.7684463543.

The spelling of 639987903 in words is "six hundred thirty-nine million, nine hundred eighty-seven thousand, nine hundred three".