639461329921 has 4 divisors (see below), whose sum is σ = 640514808832. Its totient is φ = 638407851012.

The previous prime is 639461329849. The next prime is 639461329931. The reversal of 639461329921 is 129923164936.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 639461329921 - 2²³ = 639452941313 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (639461329931) 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 3 ways as a sum of consecutive naturals, for example, 526738545 + ... + 526739758.

It is an arithmetic number, because the mean of its divisors is an integer number (160128702208).

Almost surely, 2^639461329921 is an apocalyptic number.

It is an amenable number.

639461329921 is a deficient number, since it is larger than the sum of its proper divisors (1053478911).

639461329921 is a wasteful number, since it uses less digits than its factorization.

639461329921 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1053478910.

The product of its digits is 3779136, while the sum is 55.

The spelling of 639461329921 in words is "six hundred thirty-nine billion, four hundred sixty-one million, three hundred twenty-nine thousand, nine hundred twenty-one".