18369581 has 2 divisors, whose sum is σ = 18369582. Its totient is φ = 18369580.

The previous prime is 18369553. The next prime is 18369583. The reversal of 18369581 is 18596381.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16240900 + 2128681 = 4030^2 + 1459^2 .

It is a cyclic number.

It is not a de Polignac number, because 18369581 - 2¹⁰ = 18368557 is a prime.

It is a super-2 number, since 2×18369581² = 674883012231122, which contains 22 as substring.

Together with 18369583, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (18369583) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 9184790 + 9184791.

It is an arithmetic number, because the mean of its divisors is an integer number (9184791).

Almost surely, 2^18369581 is an apocalyptic number.

It is an amenable number.

18369581 is a deficient number, since it is larger than the sum of its proper divisors (1).

18369581 is an equidigital number, since it uses as much as digits as its factorization.

18369581 is an evil number, because the sum of its binary digits is even.

The product of its digits is 51840, while the sum is 41.

The square root of 18369581 is about 4285.9749182654. The cubic root of 18369581 is about 263.8556612658.

The spelling of 18369581 in words is "eighteen million, three hundred sixty-nine thousand, five hundred eighty-one".