18491556632761 has 3 divisors (see below), whose sum is σ = 18491560932943. Its totient is φ = 18491552332580.

The previous prime is 18491556632743. The next prime is 18491556632831. The reversal of 18491556632761 is 16723665519481.

The square root of 18491556632761 is 4300181.

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

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It can be written as a sum of positive squares in only one way, i.e., 581224789161 + 17910331843600 = 762381^2 + 4232060^2 .

It is not a de Polignac number, because 18491556632761 - 2⁵ = 18491556632729 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 18491556632693 and 18491556632702.

It is not an unprimeable number, because it can be changed into a prime (18491556632161) by changing a digit.

It is a polite number, since it can be written in 2 ways as a sum of consecutive naturals, for example, 2150091 + ... + 6450271.

Almost surely, 2^{18491556632761} is an apocalyptic number.

18491556632761 is the 4300181-st square number.

18491556632761 is the 2150091-st centered octagonal number.

It is an amenable number.

18491556632761 is a deficient number, since it is larger than the sum of its proper divisors (4300182).

18491556632761 is an frugal number, since it uses more digits than its factorization.

18491556632761 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8600362 (or 4300181 counting only the distinct ones).

The product of its digits is 65318400, while the sum is 64.

The spelling of 18491556632761 in words is "eighteen trillion, four hundred ninety-one billion, five hundred fifty-six million, six hundred thirty-two thousand, seven hundred sixty-one".