21056249 has 2 divisors, whose sum is σ = 21056250. Its totient is φ = 21056248.

The previous prime is 21056227. The next prime is 21056263. The reversal of 21056249 is 94265012.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11102224 + 9954025 = 3332^2 + 3155^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21056249 is a prime.

It is not a weakly prime, because it can be changed into another prime (21056549) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10528124 + 10528125.

It is an arithmetic number, because the mean of its divisors is an integer number (10528125).

Almost surely, 2^21056249 is an apocalyptic number.

It is an amenable number.

21056249 is a deficient number, since it is larger than the sum of its proper divisors (1).

21056249 is an equidigital number, since it uses as much as digits as its factorization.

21056249 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4320, while the sum is 29.

The square root of 21056249 is about 4588.7088597992. The cubic root of 21056249 is about 276.1385261694.

The spelling of 21056249 in words is "twenty-one million, fifty-six thousand, two hundred forty-nine".