8721028 has 18 divisors (see below), whose sum is σ = 15655178. Its totient is φ = 4250880.

The previous prime is 8720977. The next prime is 8721029. The reversal of 8721028 is 8201278.

It can be written as a sum of positive squares in 3 ways, for example, as 322624 + 8398404 = 568^2 + 2898^2 .

It is a junction number, because it is equal to n+sod(n) for n = 8720987 and 8721005.

It is not an unprimeable number, because it can be changed into a prime (8721029) by changing a digit.

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 in 5 ways as a sum of consecutive naturals, for example, 6076 + ... + 7372.

Almost surely, 2^8721028 is an apocalyptic number.

It is an amenable number.

8721028 is a deficient number, since it is larger than the sum of its proper divisors (6934150).

8721028 is a wasteful number, since it uses less digits than its factorization.

8721028 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1383 (or 1340 counting only the distinct ones).

The product of its (nonzero) digits is 1792, while the sum is 28.

The square root of 8721028 is about 2953.1386692805. The cubic root of 8721028 is about 205.8365813639.

It can be divided in two parts, 87 and 21028, that added together give a triangular number (21115 = T₂₀₅).

The spelling of 8721028 in words is "eight million, seven hundred twenty-one thousand, twenty-eight".