21795817 has 2 divisors, whose sum is σ = 21795818. Its totient is φ = 21795816.

The previous prime is 21795757. The next prime is 21795847. The reversal of 21795817 is 71859712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14714896 + 7080921 = 3836^2 + 2661^2 .

It is a cyclic number.

It is not a de Polignac number, because 21795817 - 2¹¹ = 21793769 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21795817.

It is not a weakly prime, because it can be changed into another prime (21795847) 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, 10897908 + 10897909.

It is an arithmetic number, because the mean of its divisors is an integer number (10897909).

Almost surely, 2^21795817 is an apocalyptic number.

It is an amenable number.

21795817 is a deficient number, since it is larger than the sum of its proper divisors (1).

21795817 is an equidigital number, since it uses as much as digits as its factorization.

21795817 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 35280, while the sum is 40.

The square root of 21795817 is about 4668.5990403975. The cubic root of 21795817 is about 279.3343755440.

The spelling of 21795817 in words is "twenty-one million, seven hundred ninety-five thousand, eight hundred seventeen".