18791339681 has 2 divisors, whose sum is σ = 18791339682. Its totient is φ = 18791339680.

The previous prime is 18791339669. The next prime is 18791339683. The reversal of 18791339681 is 18693319781.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15373768081 + 3417571600 = 123991^2 + 58460^2 .

It is a cyclic number.

It is not a de Polignac number, because 18791339681 - 2⁶ = 18791339617 is a prime.

It is a super-2 number, since 2×18791339681² (a number of 21 digits) contains 22 as substring.

Together with 18791339683, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (18791339683) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9395669840 + 9395669841.

It is an arithmetic number, because the mean of its divisors is an integer number (9395669841).

Almost surely, 2^18791339681 is an apocalyptic number.

It is an amenable number.

18791339681 is a deficient number, since it is larger than the sum of its proper divisors (1).

18791339681 is an equidigital number, since it uses as much as digits as its factorization.

18791339681 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1959552, while the sum is 56.

The spelling of 18791339681 in words is "eighteen billion, seven hundred ninety-one million, three hundred thirty-nine thousand, six hundred eighty-one".