78691991040 has 960 divisors, whose sum is σ = 307519692480. Its totient is φ = 18473287680.

The previous prime is 78691991017. The next prime is 78691991047. The reversal of 78691991040 is 4019919687.

It is a tau number, because it is divible by the number of its divisors (960).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78691991047) by changing a digit.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 1077972444 + ... + 1077972516.

It is an arithmetic number, because the mean of its divisors is an integer number (320333013).

Almost surely, 2^78691991040 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 78691991040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (153759846240).

78691991040 is an abundant number, since it is smaller than the sum of its proper divisors (228827701440).

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

78691991040 is a wasteful number, since it uses less digits than its factorization.

78691991040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 235 (or 216 counting only the distinct ones).

The product of its (nonzero) digits is 979776, while the sum is 54.

The spelling of 78691991040 in words is "seventy-eight billion, six hundred ninety-one million, nine hundred ninety-one thousand, forty".