639993531 has 8 divisors (see below), whose sum is σ = 854958400. Its totient is φ = 425845512.

The previous prime is 639993491. The next prime is 639993533. The reversal of 639993531 is 135399936.

639993531 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 not a de Polignac number, because 639993531 - 2⁹ = 639993019 is a prime.

It is a super-2 number, since 2×639993531² = 819183439443695922, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (639993533) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 202381 + ... + 205518.

It is an arithmetic number, because the mean of its divisors is an integer number (106869800).

Almost surely, 2^639993531 is an apocalyptic number.

639993531 is a deficient number, since it is larger than the sum of its proper divisors (214964869).

639993531 is a wasteful number, since it uses less digits than its factorization.

639993531 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 408425.

The product of its digits is 590490, while the sum is 48.

The square root of 639993531 is about 25298.0934261853. The cubic root of 639993531 is about 861.7709724534.

The spelling of 639993531 in words is "six hundred thirty-nine million, nine hundred ninety-three thousand, five hundred thirty-one".