639992387 has 16 divisors (see below), whose sum is σ = 710648640. Its totient is φ = 573576192.

The previous prime is 639992377. The next prime is 639992401. The reversal of 639992387 is 783299936.

It is not a de Polignac number, because 639992387 - 2¹² = 639988291 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (639992357) 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 15 ways as a sum of consecutive naturals, for example, 27098 + ... + 44880.

It is an arithmetic number, because the mean of its divisors is an integer number (44415540).

Almost surely, 2^639992387 is an apocalyptic number.

639992387 is a deficient number, since it is larger than the sum of its proper divisors (70656253).

639992387 is a wasteful number, since it uses less digits than its factorization.

639992387 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17902.

The product of its digits is 4408992, while the sum is 56.

The square root of 639992387 is about 25298.0708157757. The cubic root of 639992387 is about 861.7704589760.

The spelling of 639992387 in words is "six hundred thirty-nine million, nine hundred ninety-two thousand, three hundred eighty-seven".