18757767681 has 27 divisors (see below), whose sum is σ = 27524347617. Its totient is φ = 12309874920.

The previous prime is 18757767659. The next prime is 18757767709. The reversal of 18757767681 is 18676775781.

The square root of 18757767681 is 136959.

It is a perfect power (a square), and thus also a powerful number.

It is not a de Polignac number, because 18757767681 - 2⁹ = 18757767169 is a prime.

It is a super-2 number, since 2×18757767681² (a number of 21 digits) contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (18757768681) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 26 ways as a sum of consecutive naturals, for example, 29171946 + ... + 29172588.

Almost surely, 2^18757767681 is an apocalyptic number.

18757767681 is the 136959-th square number.

18757767681 is the 68480-th centered octagonal number.

It is an amenable number.

18757767681 is a deficient number, since it is larger than the sum of its proper divisors (8766579936).

18757767681 is an frugal number, since it uses more digits than its factorization.

18757767681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1434 (or 717 counting only the distinct ones).

The product of its digits is 27659520, while the sum is 63.

The spelling of 18757767681 in words is "eighteen billion, seven hundred fifty-seven million, seven hundred sixty-seven thousand, six hundred eighty-one".