9813721 has 4 divisors (see below), whose sum is σ = 9885492. Its totient is φ = 9741952.

The previous prime is 9813703. The next prime is 9813731. The reversal of 9813721 is 1273189.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1273189 = 131 ⋅9719.

It can be written as a sum of positive squares in 2 ways, for example, as 3463321 + 6350400 = 1861^2 + 2520^2 .

It is a cyclic number.

It is not a de Polignac number, because 9813721 - 2⁷ = 9813593 is a prime.

It is a Smith number, since the sum of its digits (31) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (9813731) 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, 35680 + ... + 35953.

It is an arithmetic number, because the mean of its divisors is an integer number (2471373).

Almost surely, 2^9813721 is an apocalyptic number.

It is an amenable number.

9813721 is a deficient number, since it is larger than the sum of its proper divisors (71771).

9813721 is a wasteful number, since it uses less digits than its factorization.

9813721 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 71770.

The product of its digits is 3024, while the sum is 31.

The square root of 9813721 is about 3132.6859082902. The cubic root of 9813721 is about 214.0973223156.

The spelling of 9813721 in words is "nine million, eight hundred thirteen thousand, seven hundred twenty-one".