21013249 has 2 divisors, whose sum is σ = 21013250. Its totient is φ = 21013248.

The previous prime is 21013217. The next prime is 21013271. The reversal of 21013249 is 94231012.

It is an a-pointer prime, because the next prime (21013271) can be obtained adding 21013249 to its sum of digits (22).

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15523600 + 5489649 = 3940^2 + 2343^2 .

It is a cyclic number.

It is not a de Polignac number, because 21013249 - 2⁵ = 21013217 is a prime.

It is not a weakly prime, because it can be changed into another prime (21013049) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10506624 + 10506625.

It is an arithmetic number, because the mean of its divisors is an integer number (10506625).

Almost surely, 2^21013249 is an apocalyptic number.

It is an amenable number.

21013249 is a deficient number, since it is larger than the sum of its proper divisors (1).

21013249 is an equidigital number, since it uses as much as digits as its factorization.

21013249 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 432, while the sum is 22.

The square root of 21013249 is about 4584.0210514351. The cubic root of 21013249 is about 275.9504260539.

The spelling of 21013249 in words is "twenty-one million, thirteen thousand, two hundred forty-nine".