18661881 has 8 divisors (see below), whose sum is σ = 28437184. Its totient is φ = 10663920.

The previous prime is 18661879. The next prime is 18661891. The reversal of 18661881 is 18816681.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 18661881 - 2¹ = 18661879 is a prime.

It is a super-2 number, since 2×18661881² = 696531604916322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18661831) 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, 444310 + ... + 444351.

It is an arithmetic number, because the mean of its divisors is an integer number (3554648).

Almost surely, 2^18661881 is an apocalyptic number.

It is an amenable number.

18661881 is a deficient number, since it is larger than the sum of its proper divisors (9775303).

18661881 is an equidigital number, since it uses as much as digits as its factorization.

18661881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 888671.

The product of its digits is 18432, while the sum is 39.

The square root of 18661881 is about 4319.9399301379. The cubic root of 18661881 is about 265.2478090157.

The spelling of 18661881 in words is "eighteen million, six hundred sixty-one thousand, eight hundred eighty-one".