21604369 has 2 divisors, whose sum is σ = 21604370. Its totient is φ = 21604368.

The previous prime is 21604339. The next prime is 21604379. The reversal of 21604369 is 96340612.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17139600 + 4464769 = 4140^2 + 2113^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21604369 is a prime.

It is a super-2 number, since 2×21604369² = 933497519776322, which contains 22 as substring.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21604369.

It is not a weakly prime, because it can be changed into another prime (21604339) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10802184 + 10802185.

It is an arithmetic number, because the mean of its divisors is an integer number (10802185).

Almost surely, 2^21604369 is an apocalyptic number.

It is an amenable number.

21604369 is a deficient number, since it is larger than the sum of its proper divisors (1).

21604369 is an equidigital number, since it uses as much as digits as its factorization.

21604369 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7776, while the sum is 31.

The square root of 21604369 is about 4648.0500212455. The cubic root of 21604369 is about 278.5141056969.

The spelling of 21604369 in words is "twenty-one million, six hundred four thousand, three hundred sixty-nine".