7978440 has 64 divisors (see below), whose sum is σ = 25349760. Its totient is φ = 2001920.

The previous prime is 7978429. The next prime is 7978441. The reversal of 7978440 is 448797.

It is not an unprimeable number, because it can be changed into a prime (7978441) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 85 + ... + 3995.

It is an arithmetic number, because the mean of its divisors is an integer number (396090).

Almost surely, 2^7978440 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 7978440, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (12674880).

7978440 is an abundant number, since it is smaller than the sum of its proper divisors (17371320).

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

7978440 is a wasteful number, since it uses less digits than its factorization.

7978440 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3942 (or 3938 counting only the distinct ones).

The product of its (nonzero) digits is 56448, while the sum is 39.

The square root of 7978440 is about 2824.6132478624. The cubic root of 7978440 is about 199.8201716907.

The spelling of 7978440 in words is "seven million, nine hundred seventy-eight thousand, four hundred forty".