639913989 has 16 divisors (see below), whose sum is σ = 1002383424. Its totient is φ = 357993600.

The previous prime is 639913969. The next prime is 639913993. The reversal of 639913989 is 989319936.

It is not a de Polignac number, because 639913989 - 2⁷ = 639913861 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639913919) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 745392 + ... + 746249.

It is an arithmetic number, because the mean of its divisors is an integer number (62648964).

Almost surely, 2^639913989 is an apocalyptic number.

It is an amenable number.

639913989 is a deficient number, since it is larger than the sum of its proper divisors (362469435).

639913989 is a wasteful number, since it uses less digits than its factorization.

639913989 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1491668.

The product of its digits is 2834352, while the sum is 57.

The square root of 639913989 is about 25296.5212825795. The cubic root of 639913989 is about 861.7352690578.

It can be divided in two parts, 639 and 913989, that added together give a triangular number (914628 = T₁₃₅₂).

The spelling of 639913989 in words is "six hundred thirty-nine million, nine hundred thirteen thousand, nine hundred eighty-nine".