18561131712 has 84 divisors (see below), whose sum is σ = 54334172256. Its totient is φ = 6055395840.

The previous prime is 18561131669. The next prime is 18561131713. The reversal of 18561131712 is 21713116581.

It is a happy number.

18561131712 is a `hidden beast` number, since 1 + 8 + 5 + 611 + 31 + 7 + 1 + 2 = 666.

It is a super-2 number, since 2×18561131712² (a number of 21 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is not an unprimeable number, because it can be changed into a prime (18561131713) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 315739 + ... + 369882.

It is an arithmetic number, because the mean of its divisors is an integer number (646835384).

Almost surely, 2^18561131712 is an apocalyptic number.

18561131712 is a gapful number since it is divisible by the number (12) formed by its first and last digit.

It is an amenable number.

18561131712 is an abundant number, since it is smaller than the sum of its proper divisors (35773040544).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

18561131712 is a wasteful number, since it uses less digits than its factorization.

18561131712 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 685686 (or 685673 counting only the distinct ones).

The product of its digits is 10080, while the sum is 36.

The spelling of 18561131712 in words is "eighteen billion, five hundred sixty-one million, one hundred thirty-one thousand, seven hundred twelve".