21798189 has 18 divisors (see below), whose sum is σ = 36627630. Its totient is φ = 12455856.

The previous prime is 21798163. The next prime is 21798197. The reversal of 21798189 is 98189712.

It can be written as a sum of positive squares in only one way, i.e., 19448100 + 2350089 = 4410^2 + 1533^2 .

It is not a de Polignac number, because 21798189 - 2⁵ = 21798157 is a prime.

It is a super-2 number, since 2×21798189² = 950322087359442, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21798389) 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 17 ways as a sum of consecutive naturals, for example, 24274 + ... + 25155.

Almost surely, 2^21798189 is an apocalyptic number.

It is an amenable number.

21798189 is a deficient number, since it is larger than the sum of its proper divisors (14829441).

21798189 is a wasteful number, since it uses less digits than its factorization.

21798189 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 49449 (or 49439 counting only the distinct ones).

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

The square root of 21798189 is about 4668.8530711514. The cubic root of 21798189 is about 279.3445083308.

The spelling of 21798189 in words is "twenty-one million, seven hundred ninety-eight thousand, one hundred eighty-nine".