8557821 has 6 divisors (see below), whose sum is σ = 12361310. Its totient is φ = 5705208.

The previous prime is 8557819. The next prime is 8557853. The reversal of 8557821 is 1287558.

8557821 is a `hidden beast` number, since 85 + 578 + 2 + 1 = 666.

8557821 is digitally balanced in base 2 and base 4, because in such bases it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in only one way, i.e., 7901721 + 656100 = 2811^2 + 810^2 .

It is not a de Polignac number, because 8557821 - 2¹ = 8557819 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (8557121) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 475426 + ... + 475443.

Almost surely, 2^8557821 is an apocalyptic number.

It is an amenable number.

8557821 is a deficient number, since it is larger than the sum of its proper divisors (3803489).

8557821 is a wasteful number, since it uses less digits than its factorization.

8557821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 950875 (or 950872 counting only the distinct ones).

The product of its digits is 22400, while the sum is 36.

The square root of 8557821 is about 2925.3753605307. The cubic root of 8557821 is about 204.5444653959.

The spelling of 8557821 in words is "eight million, five hundred fifty-seven thousand, eight hundred twenty-one".