21986417 has 2 divisors, whose sum is σ = 21986418. Its totient is φ = 21986416.

The previous prime is 21986407. The next prime is 21986431. The reversal of 21986417 is 71468912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21169201 + 817216 = 4601^2 + 904^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21986417 is a prime.

It is not a weakly prime, because it can be changed into another prime (21986407) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10993208 + 10993209.

It is an arithmetic number, because the mean of its divisors is an integer number (10993209).

Almost surely, 2^21986417 is an apocalyptic number.

It is an amenable number.

21986417 is a deficient number, since it is larger than the sum of its proper divisors (1).

21986417 is an equidigital number, since it uses as much as digits as its factorization.

21986417 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 24192, while the sum is 38.

The square root of 21986417 is about 4688.9675835945. The cubic root of 21986417 is about 280.1462543749.

The spelling of 21986417 in words is "twenty-one million, nine hundred eighty-six thousand, four hundred seventeen".