21930817 has 8 divisors (see below), whose sum is σ = 22866624. Its totient is φ = 21014448.

The previous prime is 21930809. The next prime is 21930851. The reversal of 21930817 is 71803912.

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 21930817 - 2³ = 21930809 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21930877) 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 7 ways as a sum of consecutive naturals, for example, 2533 + ... + 7090.

It is an arithmetic number, because the mean of its divisors is an integer number (2858328).

Almost surely, 2^21930817 is an apocalyptic number.

It is an amenable number.

21930817 is a deficient number, since it is larger than the sum of its proper divisors (935807).

21930817 is an equidigital number, since it uses as much as digits as its factorization.

21930817 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9719.

The product of its (nonzero) digits is 3024, while the sum is 31.

The square root of 21930817 is about 4683.0350201552. The cubic root of 21930817 is about 279.9099072394.

The spelling of 21930817 in words is "twenty-one million, nine hundred thirty thousand, eight hundred seventeen".