9725821 has 4 divisors (see below), whose sum is σ = 11115232. Its totient is φ = 8336412.

The previous prime is 9725809. The next prime is 9725827. The reversal of 9725821 is 1285279.

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 not a de Polignac number, because 9725821 - 2¹¹ = 9723773 is a prime.

It is a Duffinian number.

9725821 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9725827) 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, 694695 + ... + 694708.

It is an arithmetic number, because the mean of its divisors is an integer number (2778808).

Almost surely, 2^9725821 is an apocalyptic number.

It is an amenable number.

9725821 is a deficient number, since it is larger than the sum of its proper divisors (1389411).

9725821 is a wasteful number, since it uses less digits than its factorization.

9725821 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1389410.

The product of its digits is 10080, while the sum is 34.

The square root of 9725821 is about 3118.6248572087. The cubic root of 9725821 is about 213.4561919817.

It can be divided in two parts, 97258 and 21, that added together give a palindrome (97279).

The spelling of 9725821 in words is "nine million, seven hundred twenty-five thousand, eight hundred twenty-one".