18513814721 has 2 divisors, whose sum is σ = 18513814722. Its totient is φ = 18513814720.

The previous prime is 18513814703. The next prime is 18513814769. The reversal of 18513814721 is 12741831581.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18013666225 + 500148496 = 134215^2 + 22364^2 .

It is a cyclic number.

It is not a de Polignac number, because 18513814721 - 2¹⁰ = 18513813697 is a prime.

It is a super-2 number, since 2×18513814721² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (18513804721) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9256907360 + 9256907361.

It is an arithmetic number, because the mean of its divisors is an integer number (9256907361).

Almost surely, 2^18513814721 is an apocalyptic number.

It is an amenable number.

18513814721 is a deficient number, since it is larger than the sum of its proper divisors (1).

18513814721 is an equidigital number, since it uses as much as digits as its factorization.

18513814721 is an evil number, because the sum of its binary digits is even.

The product of its digits is 53760, while the sum is 41.

The spelling of 18513814721 in words is "eighteen billion, five hundred thirteen million, eight hundred fourteen thousand, seven hundred twenty-one".