21928189 has 2 divisors, whose sum is σ = 21928190. Its totient is φ = 21928188.

The previous prime is 21928171. The next prime is 21928213. The reversal of 21928189 is 98182912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12131289 + 9796900 = 3483^2 + 3130^2 .

It is a cyclic number.

It is not a de Polignac number, because 21928189 - 2¹⁵ = 21895421 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21928169) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10964094 + 10964095.

It is an arithmetic number, because the mean of its divisors is an integer number (10964095).

Almost surely, 2^21928189 is an apocalyptic number.

It is an amenable number.

21928189 is a deficient number, since it is larger than the sum of its proper divisors (1).

21928189 is an equidigital number, since it uses as much as digits as its factorization.

21928189 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 20736, while the sum is 40.

The square root of 21928189 is about 4682.7544244814. The cubic root of 21928189 is about 279.8987261295.

The spelling of 21928189 in words is "twenty-one million, nine hundred twenty-eight thousand, one hundred eighty-nine".