8721857 has 4 divisors (see below), whose sum is σ = 8742996. Its totient is φ = 8700720.

The previous prime is 8721851. The next prime is 8721877. The reversal of 8721857 is 7581278.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 101761 + 8620096 = 319^2 + 2936^2 .

It is a cyclic number.

It is not a de Polignac number, because 8721857 - 2¹⁶ = 8656321 is a prime.

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 8721857.

It is not an unprimeable number, because it can be changed into a prime (8721851) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9938 + ... + 10779.

It is an arithmetic number, because the mean of its divisors is an integer number (2185749).

Almost surely, 2^8721857 is an apocalyptic number.

It is an amenable number.

8721857 is a deficient number, since it is larger than the sum of its proper divisors (21139).

8721857 is a wasteful number, since it uses less digits than its factorization.

8721857 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 21138.

The product of its digits is 31360, while the sum is 38.

The square root of 8721857 is about 2953.2790250838. The cubic root of 8721857 is about 205.8431032678.

The spelling of 8721857 in words is "eight million, seven hundred twenty-one thousand, eight hundred fifty-seven".