21939443 has 4 divisors (see below), whose sum is σ = 22299168. Its totient is φ = 21579720.

The previous prime is 21939439. The next prime is 21939461. The reversal of 21939443 is 34493912.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21939443 - 2² = 21939439 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21939143) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 179771 + ... + 179892.

It is an arithmetic number, because the mean of its divisors is an integer number (5574792).

Almost surely, 2^21939443 is an apocalyptic number.

21939443 is a deficient number, since it is larger than the sum of its proper divisors (359725).

21939443 is an equidigital number, since it uses as much as digits as its factorization.

21939443 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 359724.

The product of its digits is 23328, while the sum is 35.

The square root of 21939443 is about 4683.9559135415. The cubic root of 21939443 is about 279.9466012115.

The spelling of 21939443 in words is "twenty-one million, nine hundred thirty-nine thousand, four hundred forty-three".