21496309 has 2 divisors, whose sum is σ = 21496310. Its totient is φ = 21496308.

The previous prime is 21496273. The next prime is 21496327. The reversal of 21496309 is 90369412.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13712209 + 7784100 = 3703^2 + 2790^2 .

It is a cyclic number.

It is not a de Polignac number, because 21496309 - 2⁹ = 21495797 is a prime.

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

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21496399) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10748154 + 10748155.

It is an arithmetic number, because the mean of its divisors is an integer number (10748155).

Almost surely, 2^21496309 is an apocalyptic number.

It is an amenable number.

21496309 is a deficient number, since it is larger than the sum of its proper divisors (1).

21496309 is an equidigital number, since it uses as much as digits as its factorization.

21496309 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 11664, while the sum is 34.

The square root of 21496309 is about 4636.4112198984. The cubic root of 21496309 is about 278.0489752061.

The spelling of 21496309 in words is "twenty-one million, four hundred ninety-six thousand, three hundred nine".