21898217 has 12 divisors (see below), whose sum is σ = 24263988. Its totient is φ = 19747200.

The previous prime is 21898189. The next prime is 21898237. The reversal of 21898217 is 71289812.

It can be written as a sum of positive squares in 2 ways, for example, as 17106496 + 4791721 = 4136^2 + 2189^2 .

It is not a de Polignac number, because 21898217 - 2⁶ = 21898153 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21898237) 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 11 ways as a sum of consecutive naturals, for example, 15917 + ... + 17237.

It is an arithmetic number, because the mean of its divisors is an integer number (2021999).

Almost surely, 2^21898217 is an apocalyptic number.

It is an amenable number.

21898217 is a deficient number, since it is larger than the sum of its proper divisors (2365771).

21898217 is a wasteful number, since it uses less digits than its factorization.

21898217 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1480 (or 1469 counting only the distinct ones).

The product of its digits is 16128, while the sum is 38.

The square root of 21898217 is about 4679.5530769508. The cubic root of 21898217 is about 279.7711437791.

The spelling of 21898217 in words is "twenty-one million, eight hundred ninety-eight thousand, two hundred seventeen".