21957443 has 4 divisors (see below), whose sum is σ = 21969600. Its totient is φ = 21945288.

The previous prime is 21957431. The next prime is 21957473. The reversal of 21957443 is 34475912.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21957443 - 2¹⁶ = 21891907 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21957473) 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, 2768 + ... + 7181.

It is an arithmetic number, because the mean of its divisors is an integer number (5492400).

Almost surely, 2^21957443 is an apocalyptic number.

21957443 is a deficient number, since it is larger than the sum of its proper divisors (12157).

21957443 is an equidigital number, since it uses as much as digits as its factorization.

21957443 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 12156.

The product of its digits is 30240, while the sum is 35.

The square root of 21957443 is about 4685.8769723500. The cubic root of 21957443 is about 280.0231400944.

The spelling of 21957443 in words is "twenty-one million, nine hundred fifty-seven thousand, four hundred forty-three".