21105443 has 2 divisors, whose sum is σ = 21105444. Its totient is φ = 21105442.

The previous prime is 21105439. The next prime is 21105457. The reversal of 21105443 is 34450112.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 21105443 - 2² = 21105439 is a prime.

It is not a weakly prime, because it can be changed into another prime (21105433) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10552721 + 10552722.

It is an arithmetic number, because the mean of its divisors is an integer number (10552722).

Almost surely, 2^21105443 is an apocalyptic number.

21105443 is a deficient number, since it is larger than the sum of its proper divisors (1).

21105443 is an equidigital number, since it uses as much as digits as its factorization.

21105443 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 480, while the sum is 20.

The square root of 21105443 is about 4594.0660639569. The cubic root of 21105443 is about 276.3534076401.

Adding to 21105443 its reverse (34450112), we get a palindrome (55555555).

The spelling of 21105443 in words is "twenty-one million, one hundred five thousand, four hundred forty-three".