9812821 has 4 divisors (see below), whose sum is σ = 9979200. Its totient is φ = 9646444.

The previous prime is 9812809. The next prime is 9812837. The reversal of 9812821 is 1282189.

It is a happy number.

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, and also an emirpimes, since its reverse is a distinct semiprime: 1282189 = 71 ⋅18059.

It is a cyclic number.

It is not a de Polignac number, because 9812821 - 2¹⁵ = 9780053 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 (9812861) 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, 83101 + ... + 83218.

It is an arithmetic number, because the mean of its divisors is an integer number (2494800).

Almost surely, 2^9812821 is an apocalyptic number.

It is an amenable number.

9812821 is a deficient number, since it is larger than the sum of its proper divisors (166379).

9812821 is a wasteful number, since it uses less digits than its factorization.

9812821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 166378.

The product of its digits is 2304, while the sum is 31.

The square root of 9812821 is about 3132.5422582944. The cubic root of 9812821 is about 214.0907772793.

The spelling of 9812821 in words is "nine million, eight hundred twelve thousand, eight hundred twenty-one".