9665781840 has 1120 divisors, whose sum is σ = 42351039360. Its totient is φ = 2015539200.

The previous prime is 9665781823. The next prime is 9665781847. The reversal of 9665781840 is 481875669.

9665781840 is a `hidden beast` number, since 9 + 66 + 578 + 1 + 8 + 4 + 0 = 666.

It is a Smith number, since the sum of its digits (54) coincides with the sum of the digits of its prime factors.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (9665781847) by changing a digit.

It is a polite number, since it can be written in 223 ways as a sum of consecutive naturals, for example, 158455410 + ... + 158455470.

It is an arithmetic number, because the mean of its divisors is an integer number (37813428).

Almost surely, 2^9665781840 is an apocalyptic number.

9665781840 is a gapful number since it is divisible by the number (90) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 9665781840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (21175519680).

9665781840 is an abundant number, since it is smaller than the sum of its proper divisors (32685257520).

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

9665781840 is a wasteful number, since it uses less digits than its factorization.

9665781840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 135 (or 114 counting only the distinct ones).

The product of its (nonzero) digits is 2903040, while the sum is 54.

The square root of 9665781840 is about 98314.7081570199. The cubic root of 9665781840 is about 2130.1605116095.

The spelling of 9665781840 in words is "nine billion, six hundred sixty-five million, seven hundred eighty-one thousand, eight hundred forty".