18039681 has 24 divisors (see below), whose sum is σ = 29038464. Its totient is φ = 10697760.

The previous prime is 18039673. The next prime is 18039689. The reversal of 18039681 is 18693081.

It is an interprime number because it is at equal distance from previous prime (18039673) and next prime (18039689).

It is not a de Polignac number, because 18039681 - 2³ = 18039673 is a prime.

It is a super-4 number, since 4×18039681⁴ (a number of 30 digits) contains 4444 as substring. Note that it is a super-d number also for d = 2.

It is not an unprimeable number, because it can be changed into a prime (18039689) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 2715 + ... + 6591.

It is an arithmetic number, because the mean of its divisors is an integer number (1209936).

Almost surely, 2^18039681 is an apocalyptic number.

18039681 is a gapful number since it is divisible by the number (11) formed by its first and last digit.

It is an amenable number.

18039681 is a deficient number, since it is larger than the sum of its proper divisors (10998783).

18039681 is a wasteful number, since it uses less digits than its factorization.

18039681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3941 (or 3938 counting only the distinct ones).

The product of its (nonzero) digits is 10368, while the sum is 36.

The square root of 18039681 is about 4247.3145633447. The cubic root of 18039681 is about 262.2665788926.

The spelling of 18039681 in words is "eighteen million, thirty-nine thousand, six hundred eighty-one".