639791999 has 16 divisors (see below), whose sum is σ = 800257536. Its totient is φ = 496917600.

The previous prime is 639791963. The next prime is 639792029. The reversal of 639791999 is 999197936.

It is a cyclic number.

It is not a de Polignac number, because 639791999 - 2⁸ = 639791743 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639791099) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 10589 + ... + 37305.

It is an arithmetic number, because the mean of its divisors is an integer number (50016096).

Almost surely, 2^639791999 is an apocalyptic number.

639791999 is a deficient number, since it is larger than the sum of its proper divisors (160465537).

639791999 is a wasteful number, since it uses less digits than its factorization.

639791999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27046.

The product of its digits is 7440174, while the sum is 62.

The square root of 639791999 is about 25294.1099665515. The cubic root of 639791999 is about 861.6805066115.

The spelling of 639791999 in words is "six hundred thirty-nine million, seven hundred ninety-one thousand, nine hundred ninety-nine".