21213312 has 32 divisors (see below), whose sum is σ = 56348880. Its totient is φ = 7070976.

The previous prime is 21213293. The next prime is 21213341. The reversal of 21213312 is 21331212.

It is a tau number, because it is divible by the number of its divisors (32).

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

It is a junction number, because it is equal to n+sod(n) for n = 21213291 and 21213300.

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, 27238 + ... + 28005.

Almost surely, 2^21213312 is an apocalyptic number.

It is an amenable number.

21213312 is an abundant number, since it is smaller than the sum of its proper divisors (35135568).

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

21213312 is an equidigital number, since it uses as much as digits as its factorization.

21213312 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55260 (or 55248 counting only the distinct ones).

The product of its digits is 72, while the sum is 15.

The square root of 21213312 is about 4605.7911372532. The cubic root of 21213312 is about 276.8234178902.

Adding to 21213312 its reverse (21331212), we get a palindrome (42544524).

The spelling of 21213312 in words is "twenty-one million, two hundred thirteen thousand, three hundred twelve".