21308612 has 12 divisors (see below), whose sum is σ = 40158636. Its totient is φ = 9834720.

The previous prime is 21308611. The next prime is 21308629. The reversal of 21308612 is 21680312.

It can be written as a sum of positive squares in 2 ways, for example, as 3041536 + 18267076 = 1744^2 + 4274^2 .

It is not an unprimeable number, because it can be changed into a prime (21308611) 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, 204839 + ... + 204942.

It is an arithmetic number, because the mean of its divisors is an integer number (3346553).

Almost surely, 2^21308612 is an apocalyptic number.

It is an amenable number.

21308612 is a deficient number, since it is larger than the sum of its proper divisors (18850024).

21308612 is a wasteful number, since it uses less digits than its factorization.

21308612 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 409798 (or 409796 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 23.

The square root of 21308612 is about 4616.1252149395. The cubic root of 21308612 is about 277.2373382375.

Adding to 21308612 its reverse (21680312), we get a palindrome (42988924).

The spelling of 21308612 in words is "twenty-one million, three hundred eight thousand, six hundred twelve".