21432231 has 6 divisors (see below), whose sum is σ = 30957680. Its totient is φ = 14288148.

The previous prime is 21432211. The next prime is 21432233. The reversal of 21432231 is 13223412.

21432231 is a `hidden beast` number, since 2 + 1 + 432 + 231 = 666.

It is not a de Polignac number, because 21432231 - 2⁵ = 21432199 is a prime.

It is a super-2 number, since 2×21432231² = 918681051274722, 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 (21432233) 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, 1190671 + ... + 1190688.

Almost surely, 2^21432231 is an apocalyptic number.

21432231 is a deficient number, since it is larger than the sum of its proper divisors (9525449).

21432231 is a wasteful number, since it uses less digits than its factorization.

21432231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2381365 (or 2381362 counting only the distinct ones).

The product of its digits is 288, while the sum is 18.

The square root of 21432231 is about 4629.4957608794. The cubic root of 21432231 is about 277.7724230020.

Adding to 21432231 its reverse (13223412), we get a palindrome (34655643).

The spelling of 21432231 in words is "twenty-one million, four hundred thirty-two thousand, two hundred thirty-one".