16199721 has 6 divisors (see below), whose sum is σ = 23399610. Its totient is φ = 10799808.

The previous prime is 16199713. The next prime is 16199749. The reversal of 16199721 is 12799161.

16199721 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 10653696 + 5546025 = 3264^2 + 2355^2 .

It is not a de Polignac number, because 16199721 - 2³ = 16199713 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (16199621) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 899976 + ... + 899993.

It is an arithmetic number, because the mean of its divisors is an integer number (3899935).

Almost surely, 2^16199721 is an apocalyptic number.

It is an amenable number.

16199721 is a deficient number, since it is larger than the sum of its proper divisors (7199889).

16199721 is a wasteful number, since it uses less digits than its factorization.

16199721 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1799975 (or 1799972 counting only the distinct ones).

The product of its digits is 6804, while the sum is 36.

The square root of 16199721 is about 4024.8877002967. The cubic root of 16199721 is about 253.0283470037.

The spelling of 16199721 in words is "sixteen million, one hundred ninety-nine thousand, seven hundred twenty-one".