21616417 has 2 divisors, whose sum is σ = 21616418. Its totient is φ = 21616416.

The previous prime is 21616373. The next prime is 21616423. The reversal of 21616417 is 71461612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 10962721 + 10653696 = 3311^2 + 3264^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21616417 is a prime.

It is not a weakly prime, because it can be changed into another prime (21616477) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10808208 + 10808209.

It is an arithmetic number, because the mean of its divisors is an integer number (10808209).

Almost surely, 2^21616417 is an apocalyptic number.

It is an amenable number.

21616417 is a deficient number, since it is larger than the sum of its proper divisors (1).

21616417 is an equidigital number, since it uses as much as digits as its factorization.

21616417 is an evil number, because the sum of its binary digits is even.

The product of its digits is 2016, while the sum is 28.

The square root of 21616417 is about 4649.3458679690. The cubic root of 21616417 is about 278.5658685970.

The spelling of 21616417 in words is "twenty-one million, six hundred sixteen thousand, four hundred seventeen".