21891093 has 24 divisors (see below), whose sum is σ = 34232832. Its totient is φ = 12406464.

The previous prime is 21891073. The next prime is 21891113. The reversal of 21891093 is 39019812.

It is an interprime number because it is at equal distance from previous prime (21891073) and next prime (21891113).

It is not a de Polignac number, because 21891093 - 2⁵ = 21891061 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21891073) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 19596 + ... + 20682.

It is an arithmetic number, because the mean of its divisors is an integer number (1426368).

Almost surely, 2^21891093 is an apocalyptic number.

It is an amenable number.

21891093 is a deficient number, since it is larger than the sum of its proper divisors (12341739).

21891093 is a wasteful number, since it uses less digits than its factorization.

21891093 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1241 (or 1234 counting only the distinct ones).

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

The square root of 21891093 is about 4678.7918312316. The cubic root of 21891093 is about 279.7408017989.

The spelling of 21891093 in words is "twenty-one million, eight hundred ninety-one thousand, ninety-three".