638636213865 has 16 divisors (see below), whose sum is σ = 1100419322688. Its totient is φ = 314405520576.

The previous prime is 638636213827. The next prime is 638636213867. The reversal of 638636213865 is 568312636836.

It is a happy number.

638636213865 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 638636213865 - 2⁷ = 638636213737 is a prime.

It is not an unprimeable number, because it can be changed into a prime (638636213867) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1637528559 + ... + 1637528948.

It is an arithmetic number, because the mean of its divisors is an integer number (68776207668).

Almost surely, 2^638636213865 is an apocalyptic number.

638636213865 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

638636213865 is a deficient number, since it is larger than the sum of its proper divisors (461783108823).

638636213865 is a wasteful number, since it uses less digits than its factorization.

638636213865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3275057528.

The product of its digits is 22394880, while the sum is 57.

The spelling of 638636213865 in words is "six hundred thirty-eight billion, six hundred thirty-six million, two hundred thirteen thousand, eight hundred sixty-five".