638660463664 has 10 divisors (see below), whose sum is σ = 1237404648380. Its totient is φ = 319330231824.

The previous prime is 638660463613. The next prime is 638660463667. The reversal of 638660463664 is 466364066836.

It is a junction number, because it is equal to n+sod(n) for n = 638660463599 and 638660463608.

It is not an unprimeable number, because it can be changed into a prime (638660463667) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 19958139474 + ... + 19958139505.

It is an arithmetic number, because the mean of its divisors is an integer number (123740464838).

Almost surely, 2^638660463664 is an apocalyptic number.

It is an amenable number.

638660463664 is a deficient number, since it is larger than the sum of its proper divisors (598744184716).

638660463664 is a wasteful number, since it uses less digits than its factorization.

638660463664 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39916278987 (or 39916278981 counting only the distinct ones).

The product of its (nonzero) digits is 53747712, while the sum is 58.

The spelling of 638660463664 in words is "six hundred thirty-eight billion, six hundred sixty million, four hundred sixty-three thousand, six hundred sixty-four".