21888891 has 12 divisors (see below), whose sum is σ = 31898568. Its totient is φ = 14462784.

The previous prime is 21888871. The next prime is 21888899. The reversal of 21888891 is 19888812.

It is not a de Polignac number, because 21888891 - 2⁵ = 21888859 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21888899) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 9745 + ... + 11778.

It is an arithmetic number, because the mean of its divisors is an integer number (2658214).

Almost surely, 2^21888891 is an apocalyptic number.

21888891 is a deficient number, since it is larger than the sum of its proper divisors (10009677).

21888891 is a wasteful number, since it uses less digits than its factorization.

21888891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21642 (or 21639 counting only the distinct ones).

The product of its digits is 73728, while the sum is 45.

The square root of 21888891 is about 4678.5565081551. The cubic root of 21888891 is about 279.7314218820.

The spelling of 21888891 in words is "twenty-one million, eight hundred eighty-eight thousand, eight hundred ninety-one".