21161889 has 24 divisors (see below), whose sum is σ = 36990720. Its totient is φ = 11380608.

The previous prime is 21161887. The next prime is 21161911. The reversal of 21161889 is 98816112.

It is not a de Polignac number, because 21161889 - 2¹ = 21161887 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21161887) 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, 8809 + ... + 10950.

It is an arithmetic number, because the mean of its divisors is an integer number (1541280).

Almost surely, 2^21161889 is an apocalyptic number.

It is an amenable number.

21161889 is a deficient number, since it is larger than the sum of its proper divisors (15828831).

21161889 is a wasteful number, since it uses less digits than its factorization.

21161889 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19789 (or 19786 counting only the distinct ones).

The product of its digits is 6912, while the sum is 36.

The square root of 21161889 is about 4600.2053215047. The cubic root of 21161889 is about 276.5995551805.

It can be divided in two parts, 2116 and 1889, that added together give a triangular number (4005 = T₈₉).

The spelling of 21161889 in words is "twenty-one million, one hundred sixty-one thousand, eight hundred eighty-nine".