18215231 has 4 divisors (see below), whose sum is σ = 18274872. Its totient is φ = 18155592.

The previous prime is 18215227. The next prime is 18215237. The reversal of 18215231 is 13251281.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 13251281 = 173 ⋅76597.

It is a cyclic number.

It is not a de Polignac number, because 18215231 - 2² = 18215227 is a prime.

It is a super-2 number, since 2×18215231² = 663589280766722, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 18215197 and 18215206.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (18215237) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 29360 + ... + 29973.

It is an arithmetic number, because the mean of its divisors is an integer number (4568718).

Almost surely, 2^18215231 is an apocalyptic number.

18215231 is a deficient number, since it is larger than the sum of its proper divisors (59641).

18215231 is an equidigital number, since it uses as much as digits as its factorization.

18215231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 59640.

The product of its digits is 480, while the sum is 23.

The square root of 18215231 is about 4267.9305289566. The cubic root of 18215231 is about 263.1145679049.

The spelling of 18215231 in words is "eighteen million, two hundred fifteen thousand, two hundred thirty-one".