21051312 has 20 divisors (see below), whose sum is σ = 54382680. Its totient is φ = 7017088.

The previous prime is 21051311. The next prime is 21051323. The reversal of 21051312 is 21315012.

It is a junction number, because it is equal to n+sod(n) for n = 21051291 and 21051300.

It is not an unprimeable number, because it can be changed into a prime (21051311) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 219237 + ... + 219332.

It is an arithmetic number, because the mean of its divisors is an integer number (2719134).

Almost surely, 2^21051312 is an apocalyptic number.

It is an amenable number.

21051312 is an abundant number, since it is smaller than the sum of its proper divisors (33331368).

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

21051312 is a wasteful number, since it uses less digits than its factorization.

21051312 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 438580 (or 438574 counting only the distinct ones).

The product of its (nonzero) digits is 60, while the sum is 15.

The square root of 21051312 is about 4588.1708773759. The cubic root of 21051312 is about 276.1169426723.

Adding to 21051312 its reverse (21315012), we get a palindrome (42366324).

The spelling of 21051312 in words is "twenty-one million, fifty-one thousand, three hundred twelve".