638844663131 has 4 divisors (see below), whose sum is σ = 639656410632. Its totient is φ = 638032915632.

The previous prime is 638844663103. The next prime is 638844663167. The reversal of 638844663131 is 131366448836.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 638844663131 - 2¹⁴ = 638844646747 is a prime.

It is a super-2 number, since 2×638844663131² (a number of 24 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (638844663101) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 405872570 + ... + 405874143.

It is an arithmetic number, because the mean of its divisors is an integer number (159914102658).

Almost surely, 2^638844663131 is an apocalyptic number.

638844663131 is a deficient number, since it is larger than the sum of its proper divisors (811747501).

638844663131 is an equidigital number, since it uses as much as digits as its factorization.

638844663131 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 811747500.

The product of its digits is 5971968, while the sum is 53.

The spelling of 638844663131 in words is "six hundred thirty-eight billion, eight hundred forty-four million, six hundred sixty-three thousand, one hundred thirty-one".