21079843 has 4 divisors (see below), whose sum is σ = 21095208. Its totient is φ = 21064480.

The previous prime is 21079823. The next prime is 21079867. The reversal of 21079843 is 34897012.

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21079843 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21079799 and 21079808.

It is not an unprimeable number, because it can be changed into a prime (21079823) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 5398 + ... + 8443.

It is an arithmetic number, because the mean of its divisors is an integer number (5273802).

Almost surely, 2^21079843 is an apocalyptic number.

21079843 is a deficient number, since it is larger than the sum of its proper divisors (15365).

21079843 is a wasteful number, since it uses less digits than its factorization.

21079843 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15364.

The product of its (nonzero) digits is 12096, while the sum is 34.

The square root of 21079843 is about 4591.2790156992. The cubic root of 21079843 is about 276.2416274770.

The spelling of 21079843 in words is "twenty-one million, seventy-nine thousand, eight hundred forty-three".