18807881 has 4 divisors (see below), whose sum is σ = 18886164. Its totient is φ = 18729600.

The previous prime is 18807871. The next prime is 18807911. The reversal of 18807881 is 18870881.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 18870881 = 3467 ⋅5443.

It can be written as a sum of positive squares in 2 ways, for example, as 7812025 + 10995856 = 2795^2 + 3316^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18807881 is a prime.

It is a super-2 number, since 2×18807881² = 707472775420322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18807821) 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, 38780 + ... + 39261.

It is an arithmetic number, because the mean of its divisors is an integer number (4721541).

Almost surely, 2^18807881 is an apocalyptic number.

It is an amenable number.

18807881 is a deficient number, since it is larger than the sum of its proper divisors (78283).

18807881 is an equidigital number, since it uses as much as digits as its factorization.

18807881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 78282.

The product of its (nonzero) digits is 28672, while the sum is 41.

The square root of 18807881 is about 4336.8053910684. The cubic root of 18807881 is about 265.9377292191.

The spelling of 18807881 in words is "eighteen million, eight hundred seven thousand, eight hundred eighty-one".