21109369 has 2 divisors, whose sum is σ = 21109370. Its totient is φ = 21109368.

The previous prime is 21109367. The next prime is 21109381. The reversal of 21109369 is 96390112.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 19035769 + 2073600 = 4363^2 + 1440^2 .

It is a cyclic number.

It is not a de Polignac number, because 21109369 - 2¹ = 21109367 is a prime.

It is a super-2 number, since 2×21109369² = 891210919156322, which contains 22 as substring.

Together with 21109367, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 21109369.

It is not a weakly prime, because it can be changed into another prime (21109367) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10554684 + 10554685.

It is an arithmetic number, because the mean of its divisors is an integer number (10554685).

Almost surely, 2^21109369 is an apocalyptic number.

It is an amenable number.

21109369 is a deficient number, since it is larger than the sum of its proper divisors (1).

21109369 is an equidigital number, since it uses as much as digits as its factorization.

21109369 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2916, while the sum is 31.

The square root of 21109369 is about 4594.4933344168. The cubic root of 21109369 is about 276.3705421807.

The spelling of 21109369 in words is "twenty-one million, one hundred nine thousand, three hundred sixty-nine".