639751994 has 8 divisors (see below), whose sum is σ = 1096717728. Its totient is φ = 274179420.

The previous prime is 639751967. The next prime is 639752023. The reversal of 639751994 is 499157936.

It is a happy number.

639751994 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a super-2 number, since 2×639751994² = 818565227653952072, which contains 22 as substring.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 22848272 + ... + 22848299.

It is an arithmetic number, because the mean of its divisors is an integer number (137089716).

Almost surely, 2^639751994 is an apocalyptic number.

639751994 is a deficient number, since it is larger than the sum of its proper divisors (456965734).

639751994 is a wasteful number, since it uses less digits than its factorization.

639751994 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 45696580.

The product of its digits is 1837080, while the sum is 53.

The square root of 639751994 is about 25293.3191574376. The cubic root of 639751994 is about 861.6625464791.

The spelling of 639751994 in words is "six hundred thirty-nine million, seven hundred fifty-one thousand, nine hundred ninety-four".