7878640 has 80 divisors (see below), whose sum is σ = 22855680. Its totient is φ = 2453760.

The previous prime is 7878613. The next prime is 7878641. The reversal of 7878640 is 468787.

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

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 = 7878593 and 7878602.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7878641) by changing a digit.

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, 5521 + ... + 6799.

It is an arithmetic number, because the mean of its divisors is an integer number (285696).

Almost surely, 2^7878640 is an apocalyptic number.

7878640 is a gapful number since it is divisible by the number (70) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 7878640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (11427840).

7878640 is an abundant number, since it is smaller than the sum of its proper divisors (14977040).

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

7878640 is a wasteful number, since it uses less digits than its factorization.

7878640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1310 (or 1304 counting only the distinct ones).

The product of its (nonzero) digits is 75264, while the sum is 40.

The square root of 7878640 is about 2806.8915191008. The cubic root of 7878640 is about 198.9835091509.

The spelling of 7878640 in words is "seven million, eight hundred seventy-eight thousand, six hundred forty".