9897821 has 4 divisors (see below), whose sum is σ = 9990432. Its totient is φ = 9805212.

The previous prime is 9897809. The next prime is 9897829. The reversal of 9897821 is 1287989.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 9897821 - 2¹⁸ = 9635677 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 (9897829) 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 3 ways as a sum of consecutive naturals, for example, 46145 + ... + 46358.

It is an arithmetic number, because the mean of its divisors is an integer number (2497608).

Almost surely, 2^9897821 is an apocalyptic number.

It is an amenable number.

9897821 is a deficient number, since it is larger than the sum of its proper divisors (92611).

9897821 is a wasteful number, since it uses less digits than its factorization.

9897821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 92610.

The product of its digits is 72576, while the sum is 44.

The square root of 9897821 is about 3146.0802596247. The cubic root of 9897821 is about 214.7071621690.

The spelling of 9897821 in words is "nine million, eight hundred ninety-seven thousand, eight hundred twenty-one".