21304612 has 36 divisors (see below), whose sum is σ = 43993740. Its totient is φ = 8999424.

The previous prime is 21304603. The next prime is 21304627. The reversal of 21304612 is 21640312.

It can be written as a sum of positive squares in 2 ways, for example, as 8156736 + 13147876 = 2856^2 + 3626^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 21304612.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 13564 + ... + 15052.

Almost surely, 2^21304612 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 21304612, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21996870).

21304612 is an abundant number, since it is smaller than the sum of its proper divisors (22689128).

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

21304612 is a wasteful number, since it uses less digits than its factorization.

21304612 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1580 (or 1571 counting only the distinct ones).

The product of its (nonzero) digits is 288, while the sum is 19.

The square root of 21304612 is about 4615.6919307943. The cubic root of 21304612 is about 277.2199897158.

Adding to 21304612 its reverse (21640312), we get a palindrome (42944924).

It can be divided in two parts, 213046 and 12, that multiplied together give a palindrome (2556552).

The spelling of 21304612 in words is "twenty-one million, three hundred four thousand, six hundred twelve".