21653708 has 12 divisors (see below), whose sum is σ = 38536680. Its totient is φ = 10643232.

The previous prime is 21653707. The next prime is 21653729. The reversal of 21653708 is 80735612.

It is a happy number.

It is not an unprimeable number, because it can be changed into a prime (21653707) 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, 45641 + ... + 46112.

It is an arithmetic number, because the mean of its divisors is an integer number (3211390).

Almost surely, 2^21653708 is an apocalyptic number.

It is an amenable number.

21653708 is a deficient number, since it is larger than the sum of its proper divisors (16882972).

21653708 is a wasteful number, since it uses less digits than its factorization.

21653708 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 91816 (or 91814 counting only the distinct ones).

The product of its (nonzero) digits is 10080, while the sum is 32.

The square root of 21653708 is about 4653.3544889681. The cubic root of 21653708 is about 278.7259634606.

The spelling of 21653708 in words is "twenty-one million, six hundred fifty-three thousand, seven hundred eight".