21422891 has 16 divisors (see below), whose sum is σ = 25436160. Its totient is φ = 17655840.

The previous prime is 21422837. The next prime is 21422897. The reversal of 21422891 is 19822412.

It is a cyclic number.

It is not a de Polignac number, because 21422891 - 2¹⁴ = 21406507 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21422897) 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 15 ways as a sum of consecutive naturals, for example, 58190 + ... + 58556.

It is an arithmetic number, because the mean of its divisors is an integer number (1589760).

Almost surely, 2^21422891 is an apocalyptic number.

21422891 is a deficient number, since it is larger than the sum of its proper divisors (4013269).

21422891 is a wasteful number, since it uses less digits than its factorization.

21422891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 674.

The product of its digits is 2304, while the sum is 29.

The square root of 21422891 is about 4628.4869017855. The cubic root of 21422891 is about 277.7320667834.

The spelling of 21422891 in words is "twenty-one million, four hundred twenty-two thousand, eight hundred ninety-one".