16721428 has 12 divisors (see below), whose sum is σ = 29291220. Its totient is φ = 8352512.

The previous prime is 16721417. The next prime is 16721443. The reversal of 16721428 is 82412761.

It can be written as a sum of positive squares in 2 ways, for example, as 13630864 + 3090564 = 3692^2 + 1758^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 16721428.

It is a congruent number.

It is an unprimeable number.

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, 6450 + ... + 8662.

It is an arithmetic number, because the mean of its divisors is an integer number (2440935).

Almost surely, 2^16721428 is an apocalyptic number.

It is an amenable number.

16721428 is a deficient number, since it is larger than the sum of its proper divisors (12569792).

16721428 is a wasteful number, since it uses less digits than its factorization.

16721428 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4106 (or 4104 counting only the distinct ones).

The product of its digits is 5376, while the sum is 31.

The square root of 16721428 is about 4089.1842707318. The cubic root of 16721428 is about 255.7159324628.

The spelling of 16721428 in words is "sixteen million, seven hundred twenty-one thousand, four hundred twenty-eight".