28721716 has 12 divisors (see below), whose sum is σ = 51996420. Its totient is φ = 13865600.

The previous prime is 28721713. The next prime is 28721723. The reversal of 28721716 is 61712782.

It is a happy number.

It can be written as a sum of positive squares in 2 ways, for example, as 17472400 + 11249316 = 4180^2 + 3354^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (28721713) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 123685 + ... + 123916.

It is an arithmetic number, because the mean of its divisors is an integer number (4333035).

Almost surely, 2^28721716 is an apocalyptic number.

It is an amenable number.

28721716 is a deficient number, since it is larger than the sum of its proper divisors (23274704).

28721716 is a wasteful number, since it uses less digits than its factorization.

28721716 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 247634 (or 247632 counting only the distinct ones).

The product of its digits is 9408, while the sum is 34.

The square root of 28721716 is about 5359.2645017763. The cubic root of 28721716 is about 306.2457905294.

The spelling of 28721716 in words is "twenty-eight million, seven hundred twenty-one thousand, seven hundred sixteen".