21631232 has 36 divisors (see below), whose sum is σ = 49350336. Its totient is φ = 9269760.

The previous prime is 21631217. The next prime is 21631237. The reversal of 21631232 is 23213612.

It is a happy number.

It is a hoax number, since the sum of its digits (20) coincides with the sum of the digits of its distinct prime factors.

It is not an unprimeable number, because it can be changed into a prime (21631237) 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, 4244 + ... + 7827.

Almost surely, 2^21631232 is an apocalyptic number.

It is an amenable number.

21631232 is an abundant number, since it is smaller than the sum of its proper divisors (27719104).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

21631232 is an equidigital number, since it uses as much as digits as its factorization.

21631232 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12094 (or 12080 counting only the distinct ones).

The product of its digits is 432, while the sum is 20.

The square root of 21631232 is about 4650.9388299568. The cubic root of 21631232 is about 278.6294932468.

Adding to 21631232 its reverse (23213612), we get a palindrome (44844844).

The spelling of 21631232 in words is "twenty-one million, six hundred thirty-one thousand, two hundred thirty-two".