16808721 has 8 divisors (see below), whose sum is σ = 22471680. Its totient is φ = 11175792.

The previous prime is 16808713. The next prime is 16808747. The reversal of 16808721 is 12780861.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 16808721 - 2³ = 16808713 is a prime.

It is a plaindrome in base 14.

It is not an unprimeable number, because it can be changed into a prime (16808221) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6166 + ... + 8463.

It is an arithmetic number, because the mean of its divisors is an integer number (2808960).

Almost surely, 2^16808721 is an apocalyptic number.

It is an amenable number.

16808721 is a deficient number, since it is larger than the sum of its proper divisors (5662959).

16808721 is a wasteful number, since it uses less digits than its factorization.

16808721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15015.

The product of its (nonzero) digits is 5376, while the sum is 33.

The square root of 16808721 is about 4099.8440214233. The cubic root of 16808721 is about 256.1601425174.

It can be divided in two parts, 1680 and 8721, that added together give a palindrome (10401).

The spelling of 16808721 in words is "sixteen million, eight hundred eight thousand, seven hundred twenty-one".