21930891 has 8 divisors (see below), whose sum is σ = 30512640. Its totient is φ = 13984872.

The previous prime is 21930877. The next prime is 21930893. The reversal of 21930891 is 19803912.

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

It is not a de Polignac number, because 21930891 - 2⁹ = 21930379 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21930893) 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 7 ways as a sum of consecutive naturals, for example, 158851 + ... + 158988.

It is an arithmetic number, because the mean of its divisors is an integer number (3814080).

Almost surely, 2^21930891 is an apocalyptic number.

21930891 is a deficient number, since it is larger than the sum of its proper divisors (8581749).

21930891 is a wasteful number, since it uses less digits than its factorization.

21930891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 317865.

The product of its (nonzero) digits is 3888, while the sum is 33.

The square root of 21930891 is about 4683.0429210077. The cubic root of 21930891 is about 279.9102220674.

The spelling of 21930891 in words is "twenty-one million, nine hundred thirty thousand, eight hundred ninety-one".