21819443 has 8 divisors (see below), whose sum is σ = 22581120. Its totient is φ = 21061440.

The previous prime is 21819437. The next prime is 21819461. The reversal of 21819443 is 34491812.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21819443 - 2¹² = 21815347 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21819403) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17021 + ... + 18257.

It is an arithmetic number, because the mean of its divisors is an integer number (2822640).

Almost surely, 2^21819443 is an apocalyptic number.

21819443 is a deficient number, since it is larger than the sum of its proper divisors (761677).

21819443 is a wasteful number, since it uses less digits than its factorization.

21819443 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1837.

The product of its digits is 6912, while the sum is 32.

The square root of 21819443 is about 4671.1286644664. The cubic root of 21819443 is about 279.4352690750.

The spelling of 21819443 in words is "twenty-one million, eight hundred nineteen thousand, four hundred forty-three".