21718616 has 16 divisors (see below), whose sum is σ = 41297040. Its totient is φ = 10706080.

The previous prime is 21718603. The next prime is 21718637. The reversal of 21718616 is 61681712.

It is a happy number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 18551 + ... + 19686.

It is an arithmetic number, because the mean of its divisors is an integer number (2581065).

Almost surely, 2^21718616 is an apocalyptic number.

It is an amenable number.

21718616 is a deficient number, since it is larger than the sum of its proper divisors (19578424).

21718616 is a wasteful number, since it uses less digits than its factorization.

21718616 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 38314 (or 38310 counting only the distinct ones).

The product of its digits is 4032, while the sum is 32.

The square root of 21718616 is about 4660.3235939149. The cubic root of 21718616 is about 279.0041836793.

The spelling of 21718616 in words is "twenty-one million, seven hundred eighteen thousand, six hundred sixteen".