21917473 has 4 divisors (see below), whose sum is σ = 22130368. Its totient is φ = 21704580.

The previous prime is 21917443. The next prime is 21917477. The reversal of 21917473 is 37471912.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21917473 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21917477) 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 3 ways as a sum of consecutive naturals, for example, 106293 + ... + 106498.

It is an arithmetic number, because the mean of its divisors is an integer number (5532592).

Almost surely, 2^21917473 is an apocalyptic number.

It is an amenable number.

21917473 is a deficient number, since it is larger than the sum of its proper divisors (212895).

21917473 is a wasteful number, since it uses less digits than its factorization.

21917473 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 212894.

The product of its digits is 10584, while the sum is 34.

The square root of 21917473 is about 4681.6100862844. The cubic root of 21917473 is about 279.8531244998.

The spelling of 21917473 in words is "twenty-one million, nine hundred seventeen thousand, four hundred seventy-three".