639657420799 has 4 divisors (see below), whose sum is σ = 639660940120. Its totient is φ = 639653901480.

The previous prime is 639657420791. The next prime is 639657420821. The reversal of 639657420799 is 997024756936.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 639657420799 - 2³ = 639657420791 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 (639657420791) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1471272 + ... + 1855789.

It is an arithmetic number, because the mean of its divisors is an integer number (159915235030).

Almost surely, 2^639657420799 is an apocalyptic number.

639657420799 is a deficient number, since it is larger than the sum of its proper divisors (3519321).

639657420799 is a wasteful number, since it uses less digits than its factorization.

639657420799 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3519320.

The product of its (nonzero) digits is 154314720, while the sum is 67.

The spelling of 639657420799 in words is "six hundred thirty-nine billion, six hundred fifty-seven million, four hundred twenty thousand, seven hundred ninety-nine".