18995681 has 6 divisors (see below), whose sum is σ = 20179110. Its totient is φ = 17878016.

The previous prime is 18995671. The next prime is 18995707. The reversal of 18995681 is 18659981.

It can be written as a sum of positive squares in 3 ways, for example, as 10240000 + 8755681 = 3200^2 + 2959^2 .

It is not a de Polignac number, because 18995681 - 2⁶ = 18995617 is a prime.

It is a super-2 number, since 2×18995681² = 721671793307522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18995621) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 32576 + ... + 33153.

It is an arithmetic number, because the mean of its divisors is an integer number (3363185).

Almost surely, 2^18995681 is an apocalyptic number.

It is an amenable number.

18995681 is a deficient number, since it is larger than the sum of its proper divisors (1183429).

18995681 is an equidigital number, since it uses as much as digits as its factorization.

18995681 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65763 (or 65746 counting only the distinct ones).

The product of its digits is 155520, while the sum is 47.

The square root of 18995681 is about 4358.4034921058. The cubic root of 18995681 is about 266.8199443457.

The spelling of 18995681 in words is "eighteen million, nine hundred ninety-five thousand, six hundred eighty-one".