21993443 has 4 divisors (see below), whose sum is σ = 22141200. Its totient is φ = 21845688.

The previous prime is 21993437. The next prime is 21993467. The reversal of 21993443 is 34439912.

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 21993443 - 2⁸ = 21993187 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21993473) 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, 73655 + ... + 73952.

It is an arithmetic number, because the mean of its divisors is an integer number (5535300).

Almost surely, 2^21993443 is an apocalyptic number.

21993443 is a deficient number, since it is larger than the sum of its proper divisors (147757).

21993443 is a wasteful number, since it uses less digits than its factorization.

21993443 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 147756.

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

The square root of 21993443 is about 4689.7167291853. The cubic root of 21993443 is about 280.1760924632.

The spelling of 21993443 in words is "twenty-one million, nine hundred ninety-three thousand, four hundred forty-three".