21866971 has 4 divisors (see below), whose sum is σ = 24990832. Its totient is φ = 18743112.

The previous prime is 21866941. The next prime is 21866989. The reversal of 21866971 is 17966812.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21866971 - 2⁷ = 21866843 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21866921) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1561920 + ... + 1561933.

It is an arithmetic number, because the mean of its divisors is an integer number (6247708).

Almost surely, 2^21866971 is an apocalyptic number.

21866971 is a deficient number, since it is larger than the sum of its proper divisors (3123861).

21866971 is an equidigital number, since it uses as much as digits as its factorization.

21866971 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3123860.

The product of its digits is 36288, while the sum is 40.

The square root of 21866971 is about 4676.2133184875. The cubic root of 21866971 is about 279.6380143674.

The spelling of 21866971 in words is "twenty-one million, eight hundred sixty-six thousand, nine hundred seventy-one".