18139881 has 8 divisors (see below), whose sum is σ = 24301984. Its totient is φ = 12035520.

The previous prime is 18139871. The next prime is 18139883. The reversal of 18139881 is 18893181.

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

It is not a de Polignac number, because 18139881 - 2¹⁸ = 17877737 is a prime.

It is a super-2 number, since 2×18139881² = 658110565388322, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18139883) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 13696 + ... + 14961.

It is an arithmetic number, because the mean of its divisors is an integer number (3037748).

Almost surely, 2^18139881 is an apocalyptic number.

It is an amenable number.

18139881 is a deficient number, since it is larger than the sum of its proper divisors (6162103).

18139881 is a wasteful number, since it uses less digits than its factorization.

18139881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28871.

The product of its digits is 13824, while the sum is 39.

The square root of 18139881 is about 4259.0939177248. The cubic root of 18139881 is about 262.7512623653.

The spelling of 18139881 in words is "eighteen million, one hundred thirty-nine thousand, eight hundred eighty-one".