21995243 has 2 divisors, whose sum is σ = 21995244. Its totient is φ = 21995242.

The previous prime is 21995209. The next prime is 21995287. The reversal of 21995243 is 34259912.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21995243 - 2¹⁶ = 21929707 is a prime.

It is a Sophie Germain prime.

It is not a weakly prime, because it can be changed into another prime (21995203) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10997621 + 10997622.

It is an arithmetic number, because the mean of its divisors is an integer number (10997622).

Almost surely, 2^21995243 is an apocalyptic number.

21995243 is a deficient number, since it is larger than the sum of its proper divisors (1).

21995243 is an equidigital number, since it uses as much as digits as its factorization.

21995243 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 19440, while the sum is 35.

The square root of 21995243 is about 4689.9086345045. The cubic root of 21995243 is about 280.1837356990.

The spelling of 21995243 in words is "twenty-one million, nine hundred ninety-five thousand, two hundred forty-three".