78640640 has 160 divisors (see below), whose sum is σ = 216548640. Its totient is φ = 27131904.

The previous prime is 78640633. The next prime is 78640673. The reversal of 78640640 is 4604687.

It is a tau number, because it is divible by the number of its divisors (160).

It is a self number, because there is not a number n which added to its sum of digits gives 78640640.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 565691 + ... + 565829.

It is an arithmetic number, because the mean of its divisors is an integer number (1353429).

Almost surely, 2^78640640 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 78640640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (108274320).

78640640 is an abundant number, since it is smaller than the sum of its proper divisors (137908000).

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

78640640 is a wasteful number, since it uses less digits than its factorization.

78640640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 192 (or 176 counting only the distinct ones).

The product of its (nonzero) digits is 32256, while the sum is 35.

The square root of 78640640 is about 8867.9557960107. The cubic root of 78640640 is about 428.4324391622.

The spelling of 78640640 in words is "seventy-eight million, six hundred forty thousand, six hundred forty".