9721731231 has 24 divisors (see below), whose sum is σ = 15056758080. Its totient is φ = 6022688256.

The previous prime is 9721731221. The next prime is 9721731263. The reversal of 9721731231 is 1321371279.

It is a happy number.

It is not a de Polignac number, because 9721731231 - 2²¹ = 9719634079 is a prime.

It is a super-2 number, since 2×9721731231² (a number of 21 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9721731221) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 390070 + ... + 414243.

It is an arithmetic number, because the mean of its divisors is an integer number (627364920).

Almost surely, 2^9721731231 is an apocalyptic number.

9721731231 is a deficient number, since it is larger than the sum of its proper divisors (5335026849).

9721731231 is a wasteful number, since it uses less digits than its factorization.

9721731231 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 804415 (or 804412 counting only the distinct ones).

The product of its digits is 15876, while the sum is 36.

The square root of 9721731231 is about 98598.8399069685. The cubic root of 9721731231 is about 2134.2626789574.

The spelling of 9721731231 in words is "nine billion, seven hundred twenty-one million, seven hundred thirty-one thousand, two hundred thirty-one".