21116839 has 4 divisors (see below), whose sum is σ = 22359024. Its totient is φ = 19874656.

The previous prime is 21116831. The next prime is 21116857. The reversal of 21116839 is 93861112.

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

It is a cyclic number.

It is not a de Polignac number, because 21116839 - 2³ = 21116831 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

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 21116839.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21116831) 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, 621067 + ... + 621100.

It is an arithmetic number, because the mean of its divisors is an integer number (5589756).

Almost surely, 2^21116839 is an apocalyptic number.

21116839 is a deficient number, since it is larger than the sum of its proper divisors (1242185).

21116839 is a wasteful number, since it uses less digits than its factorization.

21116839 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1242184.

The product of its digits is 2592, while the sum is 31.

The square root of 21116839 is about 4595.3061921922. The cubic root of 21116839 is about 276.4031382044.

The spelling of 21116839 in words is "twenty-one million, one hundred sixteen thousand, eight hundred thirty-nine".