18565381 has 2 divisors, whose sum is σ = 18565382. Its totient is φ = 18565380.

The previous prime is 18565363. The next prime is 18565403. The reversal of 18565381 is 18356581.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12489156 + 6076225 = 3534^2 + 2465^2 .

It is a cyclic number.

It is not a de Polignac number, because 18565381 - 2⁹ = 18564869 is a prime.

It is a super-2 number, since 2×18565381² = 689346743350322, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 18565381.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18565321) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9282690 + 9282691.

It is an arithmetic number, because the mean of its divisors is an integer number (9282691).

Almost surely, 2^18565381 is an apocalyptic number.

It is an amenable number.

18565381 is a deficient number, since it is larger than the sum of its proper divisors (1).

18565381 is an equidigital number, since it uses as much as digits as its factorization.

18565381 is an evil number, because the sum of its binary digits is even.

The product of its digits is 28800, while the sum is 37.

The square root of 18565381 is about 4308.7563170827. The cubic root of 18565381 is about 264.7898226678.

The spelling of 18565381 in words is "eighteen million, five hundred sixty-five thousand, three hundred eighty-one".