639693457785 has 48 divisors (see below), whose sum is σ = 1126039958784. Its totient is φ = 335904160896.

The previous prime is 639693457729. The next prime is 639693457829. The reversal of 639693457785 is 587754396936.

639693457785 is a `hidden beast` number, since 6 + 3 + 9 + 6 + 93 + 457 + 7 + 85 = 666.

639693457785 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 639693457785 - 2⁶ = 639693457721 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 402972 + ... + 1200738.

It is an arithmetic number, because the mean of its divisors is an integer number (23459165808).

Almost surely, 2^639693457785 is an apocalyptic number.

It is an amenable number.

639693457785 is a deficient number, since it is larger than the sum of its proper divisors (486346500999).

639693457785 is a wasteful number, since it uses less digits than its factorization.

639693457785 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 798054 (or 798051 counting only the distinct ones).

The product of its digits is 1028764800, while the sum is 72.

The spelling of 639693457785 in words is "six hundred thirty-nine billion, six hundred ninety-three million, four hundred fifty-seven thousand, seven hundred eighty-five".