21123232 has 24 divisors (see below), whose sum is σ = 44786196. Its totient is φ = 9748992.

The previous prime is 21123211. The next prime is 21123287. The reversal of 21123232 is 23232112.

It can be written as a sum of positive squares in 2 ways, for example, as 21123216 + 16 = 4596^2 + 4^2 .

It is a Harshad number since it is a multiple of its sum of digits (16).

21123232 is a modest number, since divided by 3232 gives 2112 as remainder.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 24973 + ... + 25804.

Almost surely, 2^21123232 is an apocalyptic number.

It is an amenable number.

21123232 is an abundant number, since it is smaller than the sum of its proper divisors (23662964).

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

21123232 is a wasteful number, since it uses less digits than its factorization.

21123232 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50800 (or 50792 counting only the distinct ones).

The product of its digits is 144, while the sum is 16.

The square root of 21123232 is about 4596.0017406437. The cubic root of 21123232 is about 276.4310285367.

Subtracting from 21123232 its sum of digits (16), we obtain a square (21123216 = 4596²).

Adding to 21123232 its reverse (23232112), we get a palindrome (44355344).

The spelling of 21123232 in words is "twenty-one million, one hundred twenty-three thousand, two hundred thirty-two".