16728121 has 4 divisors (see below), whose sum is σ = 16881700. Its totient is φ = 16574544.

The previous prime is 16728109. The next prime is 16728137. The reversal of 16728121 is 12182761.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 12182761 = 17 ⋅716633.

It can be written as a sum of positive squares in 2 ways, for example, as 14356521 + 2371600 = 3789^2 + 1540^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-16728121 is a prime.

It is a deceptive number, since it divides R_16728120.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 16728121.

It is not an unprimeable number, because it can be changed into a prime (16728191) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 76626 + ... + 76843.

It is an arithmetic number, because the mean of its divisors is an integer number (4220425).

Almost surely, 2^16728121 is an apocalyptic number.

It is an amenable number.

16728121 is a deficient number, since it is larger than the sum of its proper divisors (153579).

16728121 is a wasteful number, since it uses less digits than its factorization.

16728121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 153578.

The product of its digits is 1344, while the sum is 28.

The square root of 16728121 is about 4090.0025672364. The cubic root of 16728121 is about 255.7500459455.

The spelling of 16728121 in words is "sixteen million, seven hundred twenty-eight thousand, one hundred twenty-one".