18198581 has 4 divisors (see below), whose sum is σ = 18785664. Its totient is φ = 17611500.

The previous prime is 18198571. The next prime is 18198601. The reversal of 18198581 is 18589181.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-18198581 is a prime.

It is a super-2 number, since 2×18198581² = 662376700827122, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18198571) 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 in 3 ways as a sum of consecutive naturals, for example, 293495 + ... + 293556.

It is an arithmetic number, because the mean of its divisors is an integer number (4696416).

Almost surely, 2^18198581 is an apocalyptic number.

It is an amenable number.

18198581 is a deficient number, since it is larger than the sum of its proper divisors (587083).

18198581 is an equidigital number, since it uses as much as digits as its factorization.

18198581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 587082.

The product of its digits is 23040, while the sum is 41.

The square root of 18198581 is about 4265.9794889333. The cubic root of 18198581 is about 263.0343750700.

The spelling of 18198581 in words is "eighteen million, one hundred ninety-eight thousand, five hundred eighty-one".