21697717 has 8 divisors (see below), whose sum is σ = 22953024. Its totient is φ = 20468448.

The previous prime is 21697703. The next prime is 21697721. The reversal of 21697717 is 71779612.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21697717 - 2⁷ = 21697589 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21697717.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21697727) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4783 + ... + 8140.

It is an arithmetic number, because the mean of its divisors is an integer number (2869128).

Almost surely, 2^21697717 is an apocalyptic number.

It is an amenable number.

21697717 is a deficient number, since it is larger than the sum of its proper divisors (1255307).

21697717 is a wasteful number, since it uses less digits than its factorization.

21697717 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13019.

The product of its digits is 37044, while the sum is 40.

The square root of 21697717 is about 4658.0808279806. The cubic root of 21697717 is about 278.9146632464.

The spelling of 21697717 in words is "twenty-one million, six hundred ninety-seven thousand, seven hundred seventeen".