18915731081 has 16 divisors (see below), whose sum is σ = 21079640400. Its totient is φ = 16853453568.

The previous prime is 18915731041. The next prime is 18915731083. The reversal of 18915731081 is 18013751981.

It can be written as a sum of positive squares in 8 ways, for example, as 1724325625 + 17191405456 = 41525^2 + 131116^2 .

It is a cyclic number.

It is not a de Polignac number, because 18915731081 - 2¹⁸ = 18915468937 is a prime.

It is a super-2 number, since 2×18915731081² (a number of 21 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (18915731083) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 1800215 + ... + 1810691.

It is an arithmetic number, because the mean of its divisors is an integer number (1317477525).

Almost surely, 2^18915731081 is an apocalyptic number.

It is an amenable number.

18915731081 is a deficient number, since it is larger than the sum of its proper divisors (2163909319).

18915731081 is a wasteful number, since it uses less digits than its factorization.

18915731081 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15308.

The product of its (nonzero) digits is 60480, while the sum is 44.

The spelling of 18915731081 in words is "eighteen billion, nine hundred fifteen million, seven hundred thirty-one thousand, eighty-one".