9985821 has 8 divisors (see below), whose sum is σ = 13332480. Its totient is φ = 6648192.

The previous prime is 9985799. The next prime is 9985853. The reversal of 9985821 is 1285899.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 9985821 - 2⁷ = 9985693 is a prime.

It is a Smith number, since the sum of its digits (42) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Curzon number.

9985821 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9985891) 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 7 ways as a sum of consecutive naturals, for example, 996 + ... + 4578.

It is an arithmetic number, because the mean of its divisors is an integer number (1666560).

Almost surely, 2^9985821 is an apocalyptic number.

It is an amenable number.

9985821 is a deficient number, since it is larger than the sum of its proper divisors (3346659).

9985821 is a wasteful number, since it uses less digits than its factorization.

9985821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4515.

The product of its digits is 51840, while the sum is 42.

The square root of 9985821 is about 3160.0349681610. The cubic root of 9985821 is about 215.3415950741.

The spelling of 9985821 in words is "nine million, nine hundred eighty-five thousand, eight hundred twenty-one".