21917873 has 8 divisors (see below), whose sum is σ = 22923648. Its totient is φ = 20916544.

The previous prime is 21917867. The next prime is 21917891. The reversal of 21917873 is 37871912.

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 21917873 - 2⁶ = 21917809 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (21917803) 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, 12836 + ... + 14442.

It is an arithmetic number, because the mean of its divisors is an integer number (2865456).

Almost surely, 2^21917873 is an apocalyptic number.

21917873 is a gapful number since it is divisible by the number (23) formed by its first and last digit.

It is an amenable number.

21917873 is a deficient number, since it is larger than the sum of its proper divisors (1005775).

21917873 is a wasteful number, since it uses less digits than its factorization.

21917873 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2223.

The product of its digits is 21168, while the sum is 38.

The square root of 21917873 is about 4681.6528064349. The cubic root of 21917873 is about 279.8548269553.

The spelling of 21917873 in words is "twenty-one million, nine hundred seventeen thousand, eight hundred seventy-three".