18307381 has 16 divisors (see below), whose sum is σ = 19641600. Its totient is φ = 17035200.

The previous prime is 18307363. The next prime is 18307397. The reversal of 18307381 is 18370381.

It is a 3-Lehmer number, since φ(18307381) divides (18307381-1)³.

It is a cyclic number.

It is a Carmichael number.

It is not a de Polignac number, because 18307381 - 2⁷ = 18307253 is a prime.

It is a super-2 number, since 2×18307381² = 670320398158322, which contains 22 as substring.

It is a deceptive number, since it divides R_18307380.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18307301) 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 15 ways as a sum of consecutive naturals, for example, 139686 + ... + 139816.

It is an arithmetic number, because the mean of its divisors is an integer number (1227600).

It is a Poulet number, since it divides 2^18307380-1.

Almost surely, 2^18307381 is an apocalyptic number.

It is an amenable number.

18307381 is a deficient number, since it is larger than the sum of its proper divisors (1334219).

18307381 is a wasteful number, since it uses less digits than its factorization.

18307381 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 300.

The product of its (nonzero) digits is 4032, while the sum is 31.

The square root of 18307381 is about 4278.7125400055. The cubic root of 18307381 is about 263.5575165465.

The spelling of 18307381 in words is "eighteen million, three hundred seven thousand, three hundred eighty-one".