9666721315584 has 360 divisors, whose sum is σ = 29692873591920. Its totient is φ = 3126037708800.

The previous prime is 9666721315549. The next prime is 9666721315597. The reversal of 9666721315584 is 4855131276669.

It is a happy number.

9666721315584 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×9666721315584² (a number of 27 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 152149744 + ... + 152213264.

It is an arithmetic number, because the mean of its divisors is an integer number (82480204422).

Almost surely, 2^{9666721315584} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 9666721315584, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (14846436795960).

9666721315584 is an abundant number, since it is smaller than the sum of its proper divisors (20026152276336).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

9666721315584 is a wasteful number, since it uses less digits than its factorization.

9666721315584 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 63769 (or 63746 counting only the distinct ones).

The product of its digits is 65318400, while the sum is 63.

The spelling of 9666721315584 in words is "nine trillion, six hundred sixty-six billion, seven hundred twenty-one million, three hundred fifteen thousand, five hundred eighty-four".