21196309 has 2 divisors, whose sum is σ = 21196310. Its totient is φ = 21196308.

The previous prime is 21196283. The next prime is 21196313. The reversal of 21196309 is 90369112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15920100 + 5276209 = 3990^2 + 2297^2 .

It is a cyclic number.

It is not a de Polignac number, because 21196309 - 2⁵ = 21196277 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21196349) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10598154 + 10598155.

It is an arithmetic number, because the mean of its divisors is an integer number (10598155).

Almost surely, 2^21196309 is an apocalyptic number.

It is an amenable number.

21196309 is a deficient number, since it is larger than the sum of its proper divisors (1).

21196309 is an equidigital number, since it uses as much as digits as its factorization.

21196309 is an evil number, because the sum of its binary digits is even.

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

The square root of 21196309 is about 4603.9449388541. The cubic root of 21196309 is about 276.7494378240.

The spelling of 21196309 in words is "twenty-one million, one hundred ninety-six thousand, three hundred nine".