18139681 has 16 divisors (see below), whose sum is σ = 21565440. Its totient is φ = 14930640.

The previous prime is 18139633. The next prime is 18139711. The reversal of 18139681 is 18693181.

It is a cyclic number.

It is not a de Polignac number, because 18139681 - 2⁷ = 18139553 is a prime.

It is a super-2 number, since 2×18139681² = 658096053563522, which contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 18139681.

It is not an unprimeable number, because it can be changed into a prime (18139601) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 38610 + ... + 39076.

It is an arithmetic number, because the mean of its divisors is an integer number (1347840).

Almost surely, 2^18139681 is an apocalyptic number.

It is an amenable number.

18139681 is a deficient number, since it is larger than the sum of its proper divisors (3425759).

18139681 is a wasteful number, since it uses less digits than its factorization.

18139681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 684.

The product of its digits is 10368, while the sum is 37.

The square root of 18139681 is about 4259.0704384877. The cubic root of 18139681 is about 262.7502967131.

The spelling of 18139681 in words is "eighteen million, one hundred thirty-nine thousand, six hundred eighty-one".