21116947 has 4 divisors (see below), whose sum is σ = 21127960. Its totient is φ = 21105936.

The previous prime is 21116933. The next prime is 21116951. The reversal of 21116947 is 74961112.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length.

It is a cyclic number.

It is not a de Polignac number, because 21116947 - 2⁷ = 21116819 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21116917) 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, 1797 + ... + 6742.

It is an arithmetic number, because the mean of its divisors is an integer number (5281990).

Almost surely, 2^21116947 is an apocalyptic number.

21116947 is a deficient number, since it is larger than the sum of its proper divisors (11013).

21116947 is an equidigital number, since it uses as much as digits as its factorization.

21116947 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 11012.

The product of its digits is 3024, while the sum is 31.

The square root of 21116947 is about 4595.3179432984. The cubic root of 21116947 is about 276.4036094159.

The spelling of 21116947 in words is "twenty-one million, one hundred sixteen thousand, nine hundred forty-seven".