21116939 has 4 divisors (see below), whose sum is σ = 21167520. Its totient is φ = 21066360.

The previous prime is 21116933. The next prime is 21116951. The reversal of 21116939 is 93961112.

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 21116939 - 2¹² = 21112843 is a prime.

It is a super-2 number, since 2×21116939² = 891850225459442, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21116933) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 24659 + ... + 25500.

It is an arithmetic number, because the mean of its divisors is an integer number (5291880).

Almost surely, 2^21116939 is an apocalyptic number.

21116939 is a deficient number, since it is larger than the sum of its proper divisors (50581).

21116939 is an equidigital number, since it uses as much as digits as its factorization.

21116939 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50580.

The product of its digits is 2916, while the sum is 32.

The square root of 21116939 is about 4595.3170728471. The cubic root of 21116939 is about 276.4035745114.

The spelling of 21116939 in words is "twenty-one million, one hundred sixteen thousand, nine hundred thirty-nine".