21210312 has 16 divisors (see below), whose sum is σ = 53025840. Its totient is φ = 7070096.

The previous prime is 21210307. The next prime is 21210313. The reversal of 21210312 is 21301212.

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 (21210313) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 441858 + ... + 441905.

It is an arithmetic number, because the mean of its divisors is an integer number (3314115).

Almost surely, 2^21210312 is an apocalyptic number.

It is an amenable number.

21210312 is an abundant number, since it is smaller than the sum of its proper divisors (31815528).

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

21210312 is a wasteful number, since it uses less digits than its factorization.

21210312 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 883772 (or 883768 counting only the distinct ones).

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

The square root of 21210312 is about 4605.4654487902. The cubic root of 21210312 is about 276.8103677607.

Adding to 21210312 its reverse (21301212), we get a palindrome (42511524).

The spelling of 21210312 in words is "twenty-one million, two hundred ten thousand, three hundred twelve".