18939628513 has 4 divisors (see below), whose sum is σ = 20396523028. Its totient is φ = 17482734000.

The previous prime is 18939628489. The next prime is 18939628517. The reversal of 18939628513 is 31582693981.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 31582693981 = 137 ⋅230530613.

It can be written as a sum of positive squares in 2 ways, for example, as 1028356624 + 17911271889 = 32068^2 + 133833^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18939628513 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18939628517) 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, 728447238 + ... + 728447263.

It is an arithmetic number, because the mean of its divisors is an integer number (5099130757).

Almost surely, 2^18939628513 is an apocalyptic number.

18939628513 is a gapful number since it is divisible by the number (13) formed by its first and last digit.

It is an amenable number.

18939628513 is a deficient number, since it is larger than the sum of its proper divisors (1456894515).

18939628513 is a wasteful number, since it uses less digits than its factorization.

18939628513 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1456894514.

The product of its digits is 2799360, while the sum is 55.

The spelling of 18939628513 in words is "eighteen billion, nine hundred thirty-nine million, six hundred twenty-eight thousand, five hundred thirteen".