21616169 has 2 divisors, whose sum is σ = 21616170. Its totient is φ = 21616168.

The previous prime is 21616157. The next prime is 21616171. The reversal of 21616169 is 96161612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21279769 + 336400 = 4613^2 + 580^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21616169 is a prime.

It is a super-2 number, since 2×21616169² = 934517524473122, which contains 22 as substring.

Together with 21616171, it forms a pair of twin primes.

It is a Chen prime.

It is an alternating number because its digits alternate between even and odd.

It is not a weakly prime, because it can be changed into another prime (21616139) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10808084 + 10808085.

It is an arithmetic number, because the mean of its divisors is an integer number (10808085).

Almost surely, 2^21616169 is an apocalyptic number.

It is an amenable number.

21616169 is a deficient number, since it is larger than the sum of its proper divisors (1).

21616169 is an equidigital number, since it uses as much as digits as its factorization.

21616169 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3888, while the sum is 32.

The square root of 21616169 is about 4649.3191974740. The cubic root of 21616169 is about 278.5648032863.

The spelling of 21616169 in words is "twenty-one million, six hundred sixteen thousand, one hundred sixty-nine".