18331122781 has 2 divisors, whose sum is σ = 18331122782. Its totient is φ = 18331122780.

The previous prime is 18331122767. The next prime is 18331122809. The reversal of 18331122781 is 18722113381.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18019035225 + 312087556 = 134235^2 + 17666^2 .

It is a cyclic number.

It is not a de Polignac number, because 18331122781 - 2⁷ = 18331122653 is a prime.

It is a super-2 number, since 2×18331122781² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 18331122781.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18331120781) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9165561390 + 9165561391.

It is an arithmetic number, because the mean of its divisors is an integer number (9165561391).

Almost surely, 2^18331122781 is an apocalyptic number.

It is an amenable number.

18331122781 is a deficient number, since it is larger than the sum of its proper divisors (1).

18331122781 is an equidigital number, since it uses as much as digits as its factorization.

18331122781 is an evil number, because the sum of its binary digits is even.

The product of its digits is 16128, while the sum is 37.

The spelling of 18331122781 in words is "eighteen billion, three hundred thirty-one million, one hundred twenty-two thousand, seven hundred eighty-one".