9869857821 has 6 divisors (see below), whose sum is σ = 14256461310. Its totient is φ = 6579905208.

The previous prime is 9869857813. The next prime is 9869857843. The reversal of 9869857821 is 1287589689.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 5389028100 + 4480829721 = 73410^2 + 66939^2 .

It is not a de Polignac number, because 9869857821 - 2³ = 9869857813 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9869857801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 548325426 + ... + 548325443.

It is an arithmetic number, because the mean of its divisors is an integer number (2376076885).

Almost surely, 2^9869857821 is an apocalyptic number.

It is an amenable number.

9869857821 is a deficient number, since it is larger than the sum of its proper divisors (4386603489).

9869857821 is a wasteful number, since it uses less digits than its factorization.

9869857821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1096650875 (or 1096650872 counting only the distinct ones).

The product of its digits is 17418240, while the sum is 63.

The square root of 9869857821 is about 99347.1580922172. The cubic root of 9869857821 is about 2145.0477561213.

The spelling of 9869857821 in words is "nine billion, eight hundred sixty-nine million, eight hundred fifty-seven thousand, eight hundred twenty-one".