21842643 has 4 divisors (see below), whose sum is σ = 29123528. Its totient is φ = 14561760.

The previous prime is 21842593. The next prime is 21842651. The reversal of 21842643 is 34624812.

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

It is not a de Polignac number, because 21842643 - 2⁹ = 21842131 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21842643.

It is not an unprimeable number, because it can be changed into a prime (21842683) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3640438 + ... + 3640443.

It is an arithmetic number, because the mean of its divisors is an integer number (7280882).

Almost surely, 2^21842643 is an apocalyptic number.

21842643 is a deficient number, since it is larger than the sum of its proper divisors (7280885).

21842643 is an equidigital number, since it uses as much as digits as its factorization.

21842643 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7280884.

The product of its digits is 9216, while the sum is 30.

The square root of 21842643 is about 4673.6113445600. The cubic root of 21842643 is about 279.5342725480.

The spelling of 21842643 in words is "twenty-one million, eight hundred forty-two thousand, six hundred forty-three".