21165717 has 8 divisors (see below), whose sum is σ = 28909440. Its totient is φ = 13766240.

The previous prime is 21165671. The next prime is 21165733. The reversal of 21165717 is 71756112.

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 21165717 - 2⁸ = 21165461 is a prime.

It is a super-2 number, since 2×21165717² = 895975152248178, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21165757) 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 7 ways as a sum of consecutive naturals, for example, 85917 + ... + 86162.

It is an arithmetic number, because the mean of its divisors is an integer number (3613680).

Almost surely, 2^21165717 is an apocalyptic number.

It is an amenable number.

21165717 is a deficient number, since it is larger than the sum of its proper divisors (7743723).

21165717 is a wasteful number, since it uses less digits than its factorization.

21165717 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 172123.

The product of its digits is 2940, while the sum is 30.

The square root of 21165717 is about 4600.6213710759. The cubic root of 21165717 is about 276.6162323190.

The spelling of 21165717 in words is "twenty-one million, one hundred sixty-five thousand, seven hundred seventeen".