18397881 has 8 divisors (see below), whose sum is σ = 27256160. Its totient is φ = 12265236.

The previous prime is 18397879. The next prime is 18397903. The reversal of 18397881 is 18879381.

It is not a de Polignac number, because 18397881 - 2¹ = 18397879 is a prime.

It is a super-2 number, since 2×18397881² = 676964050580322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18397811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 340675 + ... + 340728.

It is an arithmetic number, because the mean of its divisors is an integer number (3407020).

Almost surely, 2^18397881 is an apocalyptic number.

It is an amenable number.

18397881 is a deficient number, since it is larger than the sum of its proper divisors (8858279).

18397881 is an equidigital number, since it uses as much as digits as its factorization.

18397881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 681412 (or 681406 counting only the distinct ones).

The product of its digits is 96768, while the sum is 45.

The square root of 18397881 is about 4289.2751135827. The cubic root of 18397881 is about 263.9910895753.

The spelling of 18397881 in words is "eighteen million, three hundred ninety-seven thousand, eight hundred eighty-one".