78384640 has 80 divisors (see below), whose sum is σ = 191161872. Its totient is φ = 30818304.

The previous prime is 78384617. The next prime is 78384641. The reversal of 78384640 is 4648387.

It is a tau number, because it is divible by the number of its divisors (80).

It is a super-2 number, since 2×78384640² = 12288303575859200, which contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (40).

It is a junction number, because it is equal to n+sod(n) for n = 78384593 and 78384602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78384641) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 171292 + ... + 171748.

Almost surely, 2^78384640 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 78384640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (95580936).

78384640 is an abundant number, since it is smaller than the sum of its proper divisors (112777232).

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

78384640 is an equidigital number, since it uses as much as digits as its factorization.

78384640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 547 (or 531 counting only the distinct ones).

The product of its (nonzero) digits is 129024, while the sum is 40.

The square root of 78384640 is about 8853.5100383972. The cubic root of 78384640 is about 427.9670397071.

The spelling of 78384640 in words is "seventy-eight million, three hundred eighty-four thousand, six hundred forty".