21445943 has 2 divisors, whose sum is σ = 21445944. Its totient is φ = 21445942.

The previous prime is 21445933. The next prime is 21445961. The reversal of 21445943 is 34954412.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21445943 - 2¹⁴ = 21429559 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21445933) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10722971 + 10722972.

It is an arithmetic number, because the mean of its divisors is an integer number (10722972).

Almost surely, 2^21445943 is an apocalyptic number.

21445943 is a deficient number, since it is larger than the sum of its proper divisors (1).

21445943 is an equidigital number, since it uses as much as digits as its factorization.

21445943 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 17280, while the sum is 32.

The square root of 21445943 is about 4630.9764629071. The cubic root of 21445943 is about 277.8316484971.

The spelling of 21445943 in words is "twenty-one million, four hundred forty-five thousand, nine hundred forty-three".