21312012 has 24 divisors (see below), whose sum is σ = 49847616. Its totient is φ = 7086928.

The previous prime is 21312001. The next prime is 21312017. The reversal of 21312012 is 21021312.

It is a Harshad number since it is a multiple of its sum of digits (12).

It is not an unprimeable number, because it can be changed into a prime (21312017) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3703 + ... + 7505.

It is an arithmetic number, because the mean of its divisors is an integer number (2076984).

Almost surely, 2^21312012 is an apocalyptic number.

It is an amenable number.

21312012 is an abundant number, since it is smaller than the sum of its proper divisors (28535604).

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

21312012 is a wasteful number, since it uses less digits than its factorization.

21312012 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4277 (or 4275 counting only the distinct ones).

The product of its (nonzero) digits is 24, while the sum is 12.

The square root of 21312012 is about 4616.4934744891. The cubic root of 21312012 is about 277.2520827739.

Adding to 21312012 its reverse (21021312), we get a palindrome (42333324).

The spelling of 21312012 in words is "twenty-one million, three hundred twelve thousand, twelve".