18916881 has 4 divisors (see below), whose sum is σ = 25222512. Its totient is φ = 12611252.

The previous prime is 18916873. The next prime is 18916883. The reversal of 18916881 is 18861981.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 18916881 - 2³ = 18916873 is a prime.

It is a super-2 number, since 2×18916881² = 715696773536322, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (18916883) 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, 3152811 + ... + 3152816.

It is an arithmetic number, because the mean of its divisors is an integer number (6305628).

Almost surely, 2^18916881 is an apocalyptic number.

It is an amenable number.

18916881 is a deficient number, since it is larger than the sum of its proper divisors (6305631).

18916881 is an equidigital number, since it uses as much as digits as its factorization.

18916881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6305630.

The product of its digits is 27648, while the sum is 42.

The square root of 18916881 is about 4349.3540899770. The cubic root of 18916881 is about 266.4504822538.

The spelling of 18916881 in words is "eighteen million, nine hundred sixteen thousand, eight hundred eighty-one".