18639138639 has 16 divisors (see below), whose sum is σ = 27114203520. Its totient is φ = 11295310560.

The previous prime is 18639138629. The next prime is 18639138671. The reversal of 18639138639 is 93683193681.

It is a happy number.

It is a de Polignac number, because none of the positive numbers 2^k-18639138639 is a prime.

It is a super-3 number, since 3×18639138639³ (a number of 32 digits) contains 333 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18639138629) 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, 401344 + ... + 445370.

It is an arithmetic number, because the mean of its divisors is an integer number (1694637720).

Almost surely, 2^18639138639 is an apocalyptic number.

18639138639 is a deficient number, since it is larger than the sum of its proper divisors (8475064881).

18639138639 is a wasteful number, since it uses less digits than its factorization.

18639138639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56870.

The product of its digits is 5038848, while the sum is 57.

The spelling of 18639138639 in words is "eighteen billion, six hundred thirty-nine million, one hundred thirty-eight thousand, six hundred thirty-nine".