18509002279681 has 9 divisors (see below), whose sum is σ = 18544041041673. Its totient is φ = 18474029622720.

The previous prime is 18509002279667. The next prime is 18509002279687. The reversal of 18509002279681 is 18697220090581.

The square root of 18509002279681 is 4302209.

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

It can be written as a sum of positive squares in 4 ways, for example, as 6655579585281 + 11853422694400 = 2579841^2 + 3442880^2 .

It is not a de Polignac number, because 18509002279681 - 2⁹ = 18509002279169 is a prime.

It is a super-2 number, since 2×18509002279681² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18509002279687) by changing a digit.

It is a polite number, since it can be written in 8 ways as a sum of consecutive naturals, for example, 2447953141 + ... + 2447960701.

Almost surely, 2^{18509002279681} is an apocalyptic number.

18509002279681 is the 4302209-th square number.

18509002279681 is the 2151105-th centered octagonal number.

It is an amenable number.

18509002279681 is a deficient number, since it is larger than the sum of its proper divisors (35038761992).

18509002279681 is an frugal number, since it uses more digits than its factorization.

18509002279681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16260 (or 8130 counting only the distinct ones).

The product of its (nonzero) digits is 4354560, while the sum is 58.

The spelling of 18509002279681 in words is "eighteen trillion, five hundred nine billion, two million, two hundred seventy-nine thousand, six hundred eighty-one".