21909269 has 2 divisors, whose sum is σ = 21909270. Its totient is φ = 21909268.

The previous prime is 21909263. The next prime is 21909287. The reversal of 21909269 is 96290912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 16443025 + 5466244 = 4055^2 + 2338^2 .

It is a cyclic number.

It is not a de Polignac number, because 21909269 - 2⁴ = 21909253 is a prime.

It is a super-2 number, since 2×21909269² = 960032136228722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21909263) 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, 10954634 + 10954635.

It is an arithmetic number, because the mean of its divisors is an integer number (10954635).

Almost surely, 2^21909269 is an apocalyptic number.

It is an amenable number.

21909269 is a deficient number, since it is larger than the sum of its proper divisors (1).

21909269 is an equidigital number, since it uses as much as digits as its factorization.

21909269 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 17496, while the sum is 38.

The square root of 21909269 is about 4680.7338099918. The cubic root of 21909269 is about 279.8182025670.

The spelling of 21909269 in words is "twenty-one million, nine hundred nine thousand, two hundred sixty-nine".