21445717 has 2 divisors, whose sum is σ = 21445718. Its totient is φ = 21445716.

The previous prime is 21445673. The next prime is 21445727. The reversal of 21445717 is 71754412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 18326961 + 3118756 = 4281^2 + 1766^2 .

It is a cyclic number.

It is not a de Polignac number, because 21445717 - 2¹⁵ = 21412949 is a prime.

It is a zygodrome in base 3.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21445727) 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 as a sum of consecutive naturals, namely, 10722858 + 10722859.

It is an arithmetic number, because the mean of its divisors is an integer number (10722859).

Almost surely, 2^21445717 is an apocalyptic number.

It is an amenable number.

21445717 is a deficient number, since it is larger than the sum of its proper divisors (1).

21445717 is an equidigital number, since it uses as much as digits as its factorization.

21445717 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7840, while the sum is 31.

The square root of 21445717 is about 4630.9520619415. The cubic root of 21445717 is about 277.8306725523.

The spelling of 21445717 in words is "twenty-one million, four hundred forty-five thousand, seven hundred seventeen".