16721791 has 4 divisors (see below), whose sum is σ = 16729992. Its totient is φ = 16713592.

The previous prime is 16721773. The next prime is 16721819. The reversal of 16721791 is 19712761.

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 16721791 - 2⁹ = 16721279 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (16721701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1605 + ... + 6001.

It is an arithmetic number, because the mean of its divisors is an integer number (4182498).

Almost surely, 2^16721791 is an apocalyptic number.

16721791 is a deficient number, since it is larger than the sum of its proper divisors (8201).

16721791 is an equidigital number, since it uses as much as digits as its factorization.

16721791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8200.

The product of its digits is 5292, while the sum is 34.

The square root of 16721791 is about 4089.2286558714. The cubic root of 16721791 is about 255.7177828672.

The spelling of 16721791 in words is "sixteen million, seven hundred twenty-one thousand, seven hundred ninety-one".