3978640 has 40 divisors (see below), whose sum is σ = 9483768. Its totient is φ = 1551360.

The previous prime is 3978593. The next prime is 3978641. The reversal of 3978640 is 468793.

3978640 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 246016 + 3732624 = 496^2 + 1932^2 .

It is a tau number, because it is divible by the number of its divisors (40).

It is a self number, because there is not a number n which added to its sum of digits gives 3978640.

It is not an unprimeable number, because it can be changed into a prime (3978641) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2674 + ... + 3886.

Almost surely, 2^3978640 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 3978640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (4741884).

3978640 is an abundant number, since it is smaller than the sum of its proper divisors (5505128).

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

3978640 is a wasteful number, since it uses less digits than its factorization.

3978640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1267 (or 1261 counting only the distinct ones).

The product of its (nonzero) digits is 36288, while the sum is 37.

The square root of 3978640 is about 1994.6528520021. The cubic root of 3978640 is about 158.4570433600.

The spelling of 3978640 in words is "three million, nine hundred seventy-eight thousand, six hundred forty".