78531840 has 216 divisors, whose sum is σ = 288412488. Its totient is φ = 19660800.

The previous prime is 78531829. The next prime is 78531841. The reversal of 78531840 is 4813587.

It can be written as a sum of positive squares in 4 ways, for example, as 41370624 + 37161216 = 6432^2 + 6096^2 .

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 78531795 and 78531804.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78531841) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 195640 + ... + 196040.

It is an arithmetic number, because the mean of its divisors is an integer number (1335243).

Almost surely, 2^78531840 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 78531840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (144206244).

78531840 is an abundant number, since it is smaller than the sum of its proper divisors (209880648).

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

78531840 is a wasteful number, since it uses less digits than its factorization.

78531840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 445 (or 428 counting only the distinct ones).

The product of its (nonzero) digits is 26880, while the sum is 36.

The square root of 78531840 is about 8861.8192263214. The cubic root of 78531840 is about 428.2347679894.

The spelling of 78531840 in words is "seventy-eight million, five hundred thirty-one thousand, eight hundred forty".