21708612 has 36 divisors (see below), whose sum is σ = 55171116. Its totient is φ = 7197120.

The previous prime is 21708611. The next prime is 21708623. The reversal of 21708612 is 21680712.

It can be written as a sum of positive squares in 2 ways, for example, as 21013056 + 695556 = 4584^2 + 834^2 .

It is a tau number, because it is divible by the number of its divisors (36).

It is not an unprimeable number, because it can be changed into a prime (21708611) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 5562 + ... + 8622.

It is an arithmetic number, because the mean of its divisors is an integer number (1532531).

Almost surely, 2^21708612 is an apocalyptic number.

It is an amenable number.

21708612 is an abundant number, since it is smaller than the sum of its proper divisors (33462504).

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

21708612 is a wasteful number, since it uses less digits than its factorization.

21708612 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3268 (or 3263 counting only the distinct ones).

The product of its (nonzero) digits is 1344, while the sum is 27.

The square root of 21708612 is about 4659.2501542630. The cubic root of 21708612 is about 278.9613389217.

The spelling of 21708612 in words is "twenty-one million, seven hundred eight thousand, six hundred twelve".