18236621 has 18 divisors (see below), whose sum is σ = 20768670. Its totient is φ = 15986880.

The previous prime is 18236609. The next prime is 18236623. The reversal of 18236621 is 12663281.

It can be written as a sum of positive squares in 9 ways, for example, as 17547721 + 688900 = 4189^2 + 830^2 .

It is not a de Polignac number, because 18236621 - 2²² = 14042317 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (29).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18236623) 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 17 ways as a sum of consecutive naturals, for example, 298931 + ... + 298991.

It is an arithmetic number, because the mean of its divisors is an integer number (1153815).

Almost surely, 2^18236621 is an apocalyptic number.

It is an amenable number.

18236621 is a deficient number, since it is larger than the sum of its proper divisors (2532049).

18236621 is an equidigital number, since it uses as much as digits as its factorization.

18236621 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 177 (or 103 counting only the distinct ones).

The product of its digits is 3456, while the sum is 29.

The square root of 18236621 is about 4270.4356920577. The cubic root of 18236621 is about 263.2175187278.

Multiplying 18236621 by its sum of digits (29), we get a square (528862009 = 22997²).

18236621 divided by its sum of digits (29) gives a square (628849 = 793²).

The spelling of 18236621 in words is "eighteen million, two hundred thirty-six thousand, six hundred twenty-one".