18685881 has 6 divisors (see below), whose sum is σ = 26990730. Its totient is φ = 12457248.

The previous prime is 18685871. The next prime is 18685957. The reversal of 18685881 is 18858681.

It is a happy number.

18685881 is a `hidden beast` number, since 1 + 8 + 68 + 588 + 1 = 666.

It can be written as a sum of positive squares in only one way, i.e., 18020025 + 665856 = 4245^2 + 816^2 .

It is a de Polignac number, because none of the positive numbers 2^k-18685881 is a prime.

It is a super-2 number, since 2×18685881² = 698324297492322, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (18685801) 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, 1038096 + ... + 1038113.

It is an arithmetic number, because the mean of its divisors is an integer number (4498455).

Almost surely, 2^18685881 is an apocalyptic number.

It is an amenable number.

18685881 is a deficient number, since it is larger than the sum of its proper divisors (8304849).

18685881 is a wasteful number, since it uses less digits than its factorization.

18685881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2076215 (or 2076212 counting only the distinct ones).

The product of its digits is 122880, while the sum is 45.

The square root of 18685881 is about 4322.7168540167. The cubic root of 18685881 is about 265.3614670905.

The spelling of 18685881 in words is "eighteen million, six hundred eighty-five thousand, eight hundred eighty-one".