21947249 has 2 divisors, whose sum is σ = 21947250. Its totient is φ = 21947248.

The previous prime is 21947213. The next prime is 21947269. The reversal of 21947249 is 94274912.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14684224 + 7263025 = 3832^2 + 2695^2 .

It is a cyclic number.

It is not a de Polignac number, because 21947249 - 2⁸ = 21946993 is a prime.

It is not a weakly prime, because it can be changed into another prime (21947269) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10973624 + 10973625.

It is an arithmetic number, because the mean of its divisors is an integer number (10973625).

Almost surely, 2^21947249 is an apocalyptic number.

It is an amenable number.

21947249 is a deficient number, since it is larger than the sum of its proper divisors (1).

21947249 is an equidigital number, since it uses as much as digits as its factorization.

21947249 is an evil number, because the sum of its binary digits is even.

The product of its digits is 36288, while the sum is 38.

The square root of 21947249 is about 4684.7891094477. The cubic root of 21947249 is about 279.9797987126.

The spelling of 21947249 in words is "twenty-one million, nine hundred forty-seven thousand, two hundred forty-nine".