21223236 has 24 divisors (see below), whose sum is σ = 49986720. Its totient is φ = 7007872.

The previous prime is 21223219. The next prime is 21223261. The reversal of 21223236 is 63232212.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6981 + ... + 9548.

It is an arithmetic number, because the mean of its divisors is an integer number (2082780).

Almost surely, 2^21223236 is an apocalyptic number.

It is an amenable number.

21223236 is an abundant number, since it is smaller than the sum of its proper divisors (28763484).

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

21223236 is a wasteful number, since it uses less digits than its factorization.

21223236 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16643 (or 16641 counting only the distinct ones).

The product of its digits is 864, while the sum is 21.

The square root of 21223236 is about 4606.8683506261. The cubic root of 21223236 is about 276.8665789536.

Adding to 21223236 its reverse (63232212), we get a palindrome (84455448).

The spelling of 21223236 in words is "twenty-one million, two hundred twenty-three thousand, two hundred thirty-six".