18181665 has 20 divisors (see below), whose sum is σ = 32593044. Its totient is φ = 9696672.

The previous prime is 18181649. The next prime is 18181679. The reversal of 18181665 is 56618181.

It can be written as a sum of positive squares in 2 ways, for example, as 8088336 + 10093329 = 2844^2 + 3177^2 .

It is not a de Polignac number, because 18181665 - 2⁴ = 18181649 is a prime.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is an unprimeable number.

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 19 ways as a sum of consecutive naturals, for example, 22042 + ... + 22851.

Almost surely, 2^18181665 is an apocalyptic number.

18181665 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

18181665 is a deficient number, since it is larger than the sum of its proper divisors (14411379).

18181665 is an equidigital number, since it uses as much as digits as its factorization.

18181665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 44910 (or 44901 counting only the distinct ones).

The product of its digits is 11520, while the sum is 36.

The square root of 18181665 is about 4263.9963649140. The cubic root of 18181665 is about 262.9528509695.

The spelling of 18181665 in words is "eighteen million, one hundred eighty-one thousand, six hundred sixty-five".