18968581 has 4 divisors (see below), whose sum is σ = 19622700. Its totient is φ = 18314464.

The previous prime is 18968569. The next prime is 18968591. The reversal of 18968581 is 18586981.

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 15760900 + 3207681 = 3970^2 + 1791^2 .

It is a cyclic number.

It is not a de Polignac number, because 18968581 - 2⁹ = 18968069 is a prime.

It is a super-2 number, since 2×18968581² = 719614130307122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18968561) 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, 327016 + ... + 327073.

It is an arithmetic number, because the mean of its divisors is an integer number (4905675).

Almost surely, 2^18968581 is an apocalyptic number.

It is an amenable number.

18968581 is a deficient number, since it is larger than the sum of its proper divisors (654119).

18968581 is an equidigital number, since it uses as much as digits as its factorization.

18968581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 654118.

The product of its digits is 138240, while the sum is 46.

The square root of 18968581 is about 4355.2934459115. The cubic root of 18968581 is about 266.6929986150.

The spelling of 18968581 in words is "eighteen million, nine hundred sixty-eight thousand, five hundred eighty-one".