21312449 has 2 divisors, whose sum is σ = 21312450. Its totient is φ = 21312448.

The previous prime is 21312439. The next prime is 21312457. The reversal of 21312449 is 94421312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17372224 + 3940225 = 4168^2 + 1985^2 .

It is a cyclic number.

It is not a de Polignac number, because 21312449 - 2¹⁶ = 21246913 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21312439) 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, 10656224 + 10656225.

It is an arithmetic number, because the mean of its divisors is an integer number (10656225).

Almost surely, 2^21312449 is an apocalyptic number.

It is an amenable number.

21312449 is a deficient number, since it is larger than the sum of its proper divisors (1).

21312449 is an equidigital number, since it uses as much as digits as its factorization.

21312449 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1728, while the sum is 26.

The square root of 21312449 is about 4616.5408045419. The cubic root of 21312449 is about 277.2539777668.

The spelling of 21312449 in words is "twenty-one million, three hundred twelve thousand, four hundred forty-nine".