21116791 has 4 divisors (see below), whose sum is σ = 21142800. Its totient is φ = 21090784.

The previous prime is 21116773. The next prime is 21116801. The reversal of 21116791 is 19761112.

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 21116791 - 2⁵ = 21116759 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21116701) 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, 11746 + ... + 13423.

It is an arithmetic number, because the mean of its divisors is an integer number (5285700).

Almost surely, 2^21116791 is an apocalyptic number.

21116791 is a deficient number, since it is larger than the sum of its proper divisors (26009).

21116791 is an equidigital number, since it uses as much as digits as its factorization.

21116791 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 26008.

The product of its digits is 756, while the sum is 28.

The square root of 21116791 is about 4595.3009694687. The cubic root of 21116791 is about 276.4029287766.

The spelling of 21116791 in words is "twenty-one million, one hundred sixteen thousand, seven hundred ninety-one".