21956243 has 2 divisors, whose sum is σ = 21956244. Its totient is φ = 21956242.

The previous prime is 21956227. The next prime is 21956261. The reversal of 21956243 is 34265912.

It is a happy number.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21956243 - 2⁴ = 21956227 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (21916243) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10978121 + 10978122.

It is an arithmetic number, because the mean of its divisors is an integer number (10978122).

Almost surely, 2^21956243 is an apocalyptic number.

21956243 is a deficient number, since it is larger than the sum of its proper divisors (1).

21956243 is an equidigital number, since it uses as much as digits as its factorization.

21956243 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12960, while the sum is 32.

The square root of 21956243 is about 4685.7489262657. The cubic root of 21956243 is about 280.0180388038.

The spelling of 21956243 in words is "twenty-one million, nine hundred fifty-six thousand, two hundred forty-three".