639988993 has 8 divisors (see below), whose sum is σ = 734117120. Its totient is φ = 546536160.

The previous prime is 639988981. The next prime is 639988997. The reversal of 639988993 is 399889936.

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

It is a cyclic number.

It is not a de Polignac number, because 639988993 - 2¹³ = 639980801 is a prime.

It is a super-2 number, since 2×639988993² = 819171822322308098, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (639988997) 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, 166788 + ... + 170581.

It is an arithmetic number, because the mean of its divisors is an integer number (91764640).

Almost surely, 2^639988993 is an apocalyptic number.

It is an amenable number.

639988993 is a deficient number, since it is larger than the sum of its proper divisors (94128127).

639988993 is a wasteful number, since it uses less digits than its factorization.

639988993 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 337647.

The product of its digits is 22674816, while the sum is 64.

The square root of 639988993 is about 25298.0037354729. The cubic root of 639988993 is about 861.7689355964.

The spelling of 639988993 in words is "six hundred thirty-nine million, nine hundred eighty-eight thousand, nine hundred ninety-three".