21961249 has 2 divisors, whose sum is σ = 21961250. Its totient is φ = 21961248.

The previous prime is 21961243. The next prime is 21961271. The reversal of 21961249 is 94216912.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21529600 + 431649 = 4640^2 + 657^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21961249 is a prime.

It is not a weakly prime, because it can be changed into another prime (21961243) 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, 10980624 + 10980625.

It is an arithmetic number, because the mean of its divisors is an integer number (10980625).

Almost surely, 2^21961249 is an apocalyptic number.

It is an amenable number.

21961249 is a deficient number, since it is larger than the sum of its proper divisors (1).

21961249 is an equidigital number, since it uses as much as digits as its factorization.

21961249 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 7776, while the sum is 34.

The square root of 21961249 is about 4686.2830687017. The cubic root of 21961249 is about 280.0393184581.

The spelling of 21961249 in words is "twenty-one million, nine hundred sixty-one thousand, two hundred forty-nine".