639643445901 has 24 divisors (see below), whose sum is σ = 992879394624. Its totient is φ = 395354678400.

The previous prime is 639643445879. The next prime is 639643445933. The reversal of 639643445901 is 109544346936.

It is a happy number.

639643445901 is a `hidden beast` number, since 6 + 3 + 9 + 6 + 4 + 3 + 44 + 590 + 1 = 666.

It is not a de Polignac number, because 639643445901 - 2¹¹ = 639643443853 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (639643445401) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 31188825 + ... + 31209326.

It is an arithmetic number, because the mean of its divisors is an integer number (41369974776).

Almost surely, 2^639643445901 is an apocalyptic number.

It is an amenable number.

639643445901 is a deficient number, since it is larger than the sum of its proper divisors (353235948723).

639643445901 is a wasteful number, since it uses less digits than its factorization.

639643445901 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 62398241 (or 62398238 counting only the distinct ones).

The product of its (nonzero) digits is 8398080, while the sum is 54.

The spelling of 639643445901 in words is "six hundred thirty-nine billion, six hundred forty-three million, four hundred forty-five thousand, nine hundred one".