21898417 has 2 divisors, whose sum is σ = 21898418. Its totient is φ = 21898416.

The previous prime is 21898403. The next prime is 21898433. The reversal of 21898417 is 71489812.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19351201 + 2547216 = 4399^2 + 1596^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21898417 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21898417.

It is not a weakly prime, because it can be changed into another prime (21898447) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10949208 + 10949209.

It is an arithmetic number, because the mean of its divisors is an integer number (10949209).

Almost surely, 2^21898417 is an apocalyptic number.

It is an amenable number.

21898417 is a deficient number, since it is larger than the sum of its proper divisors (1).

21898417 is an equidigital number, since it uses as much as digits as its factorization.

21898417 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 32256, while the sum is 40.

The square root of 21898417 is about 4679.5744464641. The cubic root of 21898417 is about 279.7719955084.

The spelling of 21898417 in words is "twenty-one million, eight hundred ninety-eight thousand, four hundred seventeen".