21866091 has 8 divisors (see below), whose sum is σ = 31397520. Its totient is φ = 13456032.

The previous prime is 21866081. The next prime is 21866111. The reversal of 21866091 is 19066812.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21866091 - 2⁶ = 21866027 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21866011) 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, 280296 + ... + 280373.

It is an arithmetic number, because the mean of its divisors is an integer number (3924690).

Almost surely, 2^21866091 is an apocalyptic number.

21866091 is a deficient number, since it is larger than the sum of its proper divisors (9531429).

21866091 is a wasteful number, since it uses less digits than its factorization.

21866091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 560685.

The product of its (nonzero) digits is 5184, while the sum is 33.

The square root of 21866091 is about 4676.1192243141. The cubic root of 21866091 is about 279.6342631276.

The spelling of 21866091 in words is "twenty-one million, eight hundred sixty-six thousand, ninety-one".