21223312 has 20 divisors (see below), whose sum is σ = 44858736. Its totient is φ = 9646880.

The previous prime is 21223297. The next prime is 21223333. The reversal of 21223312 is 21332212.

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

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 60118 + ... + 60469.

Almost surely, 2^21223312 is an apocalyptic number.

21223312 is a gapful number since it is divisible by the number (22) formed by its first and last digit.

It is an amenable number.

21223312 is an abundant number, since it is smaller than the sum of its proper divisors (23635424).

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

21223312 is a wasteful number, since it uses less digits than its factorization.

21223312 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 120606 (or 120600 counting only the distinct ones).

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

The square root of 21223312 is about 4606.8765991722. The cubic root of 21223312 is about 276.8669094379.

Adding to 21223312 its reverse (21332212), we get a palindrome (42555524).

Subtracting 21223312 from its reverse (21332212), we obtain a square (108900 = 330²).

The spelling of 21223312 in words is "twenty-one million, two hundred twenty-three thousand, three hundred twelve".