639643445955 has 24 divisors (see below), whose sum is σ = 1118887014960. Its totient is φ = 338013414720.

The previous prime is 639643445933. The next prime is 639643445963. The reversal of 639643445955 is 559544346936.

639643445955 is a `hidden beast` number, since 6 + 3 + 9 + 6 + 4 + 34 + 4 + 595 + 5 = 666.

It is not a de Polignac number, because 639643445955 - 2¹² = 639643441859 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 639643445892 and 639643445901.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 65198301 + ... + 65208110.

It is an arithmetic number, because the mean of its divisors is an integer number (46620292290).

Almost surely, 2^639643445955 is an apocalyptic number.

639643445955 is a deficient number, since it is larger than the sum of its proper divisors (479243569005).

639643445955 is a wasteful number, since it uses less digits than its factorization.

639643445955 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 130406531 (or 130406528 counting only the distinct ones).

The product of its digits is 209952000, while the sum is 63.

The spelling of 639643445955 in words is "six hundred thirty-nine billion, six hundred forty-three million, four hundred forty-five thousand, nine hundred fifty-five".