78128640 has 120 divisors (see below), whose sum is σ = 270661248. Its totient is φ = 20828160.

The previous prime is 78128623. The next prime is 78128641. The reversal of 78128640 is 4682187.

78128640 is a `hidden beast` number, since 7 + 8 + 1 + 2 + 8 + 640 = 666.

It is a tau number, because it is divible by the number of its divisors (120).

It is a super-2 number, since 2×78128640² = 12208168776499200, which contains 22 as substring.

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 = 78128595 and 78128604.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (78128641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 21345 + ... + 24735.

Almost surely, 2^78128640 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 78128640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (135330624).

78128640 is an abundant number, since it is smaller than the sum of its proper divisors (192532608).

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

78128640 is a wasteful number, since it uses less digits than its factorization.

78128640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3420 (or 3401 counting only the distinct ones).

The product of its (nonzero) digits is 21504, while the sum is 36.

The square root of 78128640 is about 8839.0406719281. The cubic root of 78128640 is about 427.5006258327.

The spelling of 78128640 in words is "seventy-eight million, one hundred twenty-eight thousand, six hundred forty".