21810231 has 6 divisors (see below), whose sum is σ = 31503680. Its totient is φ = 14540148.

The previous prime is 21810221. The next prime is 21810253. The reversal of 21810231 is 13201812.

It is not a de Polignac number, because 21810231 - 2⁵ = 21810199 is a prime.

It is a super-2 number, since 2×21810231² = 951372352546722, 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 (21810211) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 1211671 + ... + 1211688.

Almost surely, 2^21810231 is an apocalyptic number.

21810231 is a deficient number, since it is larger than the sum of its proper divisors (9693449).

21810231 is a wasteful number, since it uses less digits than its factorization.

21810231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2423365 (or 2423362 counting only the distinct ones).

The product of its (nonzero) digits is 96, while the sum is 18.

The square root of 21810231 is about 4670.1425031791. The cubic root of 21810231 is about 279.3959384034.

The spelling of 21810231 in words is "twenty-one million, eight hundred ten thousand, two hundred thirty-one".