21998173 has 2 divisors, whose sum is σ = 21998174. Its totient is φ = 21998172.

The previous prime is 21998159. The next prime is 21998201. The reversal of 21998173 is 37189912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15657849 + 6340324 = 3957^2 + 2518^2 .

It is a cyclic number.

It is not a de Polignac number, because 21998173 - 2¹⁷ = 21867101 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21998113) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10999086 + 10999087.

It is an arithmetic number, because the mean of its divisors is an integer number (10999087).

Almost surely, 2^21998173 is an apocalyptic number.

It is an amenable number.

21998173 is a deficient number, since it is larger than the sum of its proper divisors (1).

21998173 is an equidigital number, since it uses as much as digits as its factorization.

21998173 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 27216, while the sum is 40.

The square root of 21998173 is about 4690.2209969254. The cubic root of 21998173 is about 280.1961762965.

The spelling of 21998173 in words is "twenty-one million, nine hundred ninety-eight thousand, one hundred seventy-three".