18166267681 has 4 divisors (see below), whose sum is σ = 18169798212. Its totient is φ = 18162737152.

The previous prime is 18166267633. The next prime is 18166267699. The reversal of 18166267681 is 18676266181.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 8169267456 + 9997000225 = 90384^2 + 99985^2 .

It is a cyclic number.

It is not a de Polignac number, because 18166267681 - 2²¹ = 18164170529 is a prime.

It is a super-2 number, since 2×18166267681² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18166267601) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1757536 + ... + 1767841.

It is an arithmetic number, because the mean of its divisors is an integer number (4542449553).

Almost surely, 2^18166267681 is an apocalyptic number.

It is an amenable number.

18166267681 is a deficient number, since it is larger than the sum of its proper divisors (3530531).

18166267681 is an equidigital number, since it uses as much as digits as its factorization.

18166267681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3530530.

The product of its digits is 1161216, while the sum is 52.

The spelling of 18166267681 in words is "eighteen billion, one hundred sixty-six million, two hundred sixty-seven thousand, six hundred eighty-one".