8721728 has 14 divisors (see below), whose sum is σ = 17307306. Its totient is φ = 4360832.

The previous prime is 8721701. The next prime is 8721737. The reversal of 8721728 is 8271278.

It can be written as a sum of positive squares in only one way, i.e., 8248384 + 473344 = 2872^2 + 688^2 .

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 68075 + ... + 68202.

Almost surely, 2^8721728 is an apocalyptic number.

It is an amenable number.

8721728 is a deficient number, since it is larger than the sum of its proper divisors (8585578).

8721728 is a wasteful number, since it uses less digits than its factorization.

8721728 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 136289 (or 136279 counting only the distinct ones).

The product of its digits is 12544, while the sum is 35.

The square root of 8721728 is about 2953.2571848723. The cubic root of 8721728 is about 205.8420884269.

It can be divided in two parts, 8721 and 728, that added together give a palindrome (9449).

The spelling of 8721728 in words is "eight million, seven hundred twenty-one thousand, seven hundred twenty-eight".