21879189 has 12 divisors (see below), whose sum is σ = 31714956. Its totient is φ = 14534592.

The previous prime is 21879167. The next prime is 21879197. The reversal of 21879189 is 98197812.

It can be written as a sum of positive squares in 2 ways, for example, as 21316689 + 562500 = 4617^2 + 750^2 .

It is not a de Polignac number, because 21879189 - 2¹³ = 21870997 is a prime.

It is a super-2 number, since 2×21879189² = 957397822595442, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21879139) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1512 + ... + 6785.

It is an arithmetic number, because the mean of its divisors is an integer number (2642913).

Almost surely, 2^21879189 is an apocalyptic number.

It is an amenable number.

21879189 is a deficient number, since it is larger than the sum of its proper divisors (9835767).

21879189 is a wasteful number, since it uses less digits than its factorization.

21879189 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8596 (or 8593 counting only the distinct ones).

The product of its digits is 72576, while the sum is 45.

The square root of 21879189 is about 4677.5195349672. The cubic root of 21879189 is about 279.6900865256.

The spelling of 21879189 in words is "twenty-one million, eight hundred seventy-nine thousand, one hundred eighty-nine".