21213236 has 36 divisors (see below), whose sum is σ = 41839140. Its totient is φ = 9398400.

The previous prime is 21213193. The next prime is 21213251. The reversal of 21213236 is 63231212.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 4648336 + 16564900 = 2156^2 + 4070^2 .

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 19310 + ... + 20378.

Almost surely, 2^21213236 is an apocalyptic number.

It is an amenable number.

21213236 is a deficient number, since it is larger than the sum of its proper divisors (20625904).

21213236 is a wasteful number, since it uses less digits than its factorization.

21213236 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1136 (or 1123 counting only the distinct ones).

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

The square root of 21213236 is about 4605.7828867631. The cubic root of 21213236 is about 276.8230873021.

Adding to 21213236 its reverse (63231212), we get a palindrome (84444448).

The spelling of 21213236 in words is "twenty-one million, two hundred thirteen thousand, two hundred thirty-six".