21045312 has 112 divisors (see below), whose sum is σ = 65227200. Its totient is φ = 6635520.

The previous prime is 21045301. The next prime is 21045317. The reversal of 21045312 is 21354012.

21045312 is a `hidden beast` number, since 210 + 453 + 1 + 2 = 666.

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21045317) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (5) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 32512 + ... + 33152.

Almost surely, 2^21045312 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 21045312, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (32613600).

21045312 is an abundant number, since it is smaller than the sum of its proper divisors (44181888).

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

21045312 is a wasteful number, since it uses less digits than its factorization.

21045312 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 681 (or 665 counting only the distinct ones).

The product of its (nonzero) digits is 240, while the sum is 18.

The square root of 21045312 is about 4587.5169754454. The cubic root of 21045312 is about 276.0907074258.

Adding to 21045312 its reverse (21354012), we get a palindrome (42399324).

The spelling of 21045312 in words is "twenty-one million, forty-five thousand, three hundred twelve".