21317249 has 2 divisors, whose sum is σ = 21317250. Its totient is φ = 21317248.

The previous prime is 21317213. The next prime is 21317267. The reversal of 21317249 is 94271312.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15523600 + 5793649 = 3940^2 + 2407^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21317249 is a prime.

It is not a weakly prime, because it can be changed into another prime (21317209) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10658624 + 10658625.

It is an arithmetic number, because the mean of its divisors is an integer number (10658625).

Almost surely, 2^21317249 is an apocalyptic number.

It is an amenable number.

21317249 is a deficient number, since it is larger than the sum of its proper divisors (1).

21317249 is an equidigital number, since it uses as much as digits as its factorization.

21317249 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 3024, while the sum is 29.

The square root of 21317249 is about 4617.0606450425. The cubic root of 21317249 is about 277.2747906291.

The spelling of 21317249 in words is "twenty-one million, three hundred seventeen thousand, two hundred forty-nine".