18638913893 has 2 divisors, whose sum is σ = 18638913894. Its totient is φ = 18638913892.

The previous prime is 18638913863. The next prime is 18638913919. The reversal of 18638913893 is 39831983681.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11934907009 + 6704006884 = 109247^2 + 81878^2 .

It is a cyclic number.

It is not a de Polignac number, because 18638913893 - 2⁶ = 18638913829 is a prime.

It is a super-2 number, since 2×18638913893² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18638913833) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9319456946 + 9319456947.

It is an arithmetic number, because the mean of its divisors is an integer number (9319456947).

Almost surely, 2^18638913893 is an apocalyptic number.

It is an amenable number.

18638913893 is a deficient number, since it is larger than the sum of its proper divisors (1).

18638913893 is an equidigital number, since it uses as much as digits as its factorization.

18638913893 is an evil number, because the sum of its binary digits is even.

The product of its digits is 6718464, while the sum is 59.

The spelling of 18638913893 in words is "eighteen billion, six hundred thirty-eight million, nine hundred thirteen thousand, eight hundred ninety-three".