18109381 has 2 divisors, whose sum is σ = 18109382. Its totient is φ = 18109380.

The previous prime is 18109373. The next prime is 18109387. The reversal of 18109381 is 18390181.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18105025 + 4356 = 4255^2 + 66^2 .

It is a cyclic number.

It is not a de Polignac number, because 18109381 - 2³ = 18109373 is a prime.

It is a super-2 number, since 2×18109381² = 655899360406322, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18109387) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9054690 + 9054691.

It is an arithmetic number, because the mean of its divisors is an integer number (9054691).

Almost surely, 2^18109381 is an apocalyptic number.

It is an amenable number.

18109381 is a deficient number, since it is larger than the sum of its proper divisors (1).

18109381 is an equidigital number, since it uses as much as digits as its factorization.

18109381 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1728, while the sum is 31.

The square root of 18109381 is about 4255.5118376054. The cubic root of 18109381 is about 262.6039183415.

The spelling of 18109381 in words is "eighteen million, one hundred nine thousand, three hundred eighty-one".