7978861 has 24 divisors (see below), whose sum is σ = 9499392. Its totient is φ = 6679200.

The previous prime is 7978849. The next prime is 7978871. The reversal of 7978861 is 1688797.

It is not a de Polignac number, because 7978861 - 2¹⁵ = 7946093 is a prime.

It is a Duffinian number.

7978861 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7978871) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 130771 + ... + 130831.

It is an arithmetic number, because the mean of its divisors is an integer number (395808).

Almost surely, 2^7978861 is an apocalyptic number.

It is an amenable number.

7978861 is a deficient number, since it is larger than the sum of its proper divisors (1520531).

7978861 is a wasteful number, since it uses less digits than its factorization.

7978861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 153 (or 142 counting only the distinct ones).

The product of its digits is 169344, while the sum is 46.

The square root of 7978861 is about 2824.6877703562. The cubic root of 7978861 is about 199.8236862797.

Subtracting from 7978861 its reverse (1688797), we obtain a square (6290064 = 2508²).

The spelling of 7978861 in words is "seven million, nine hundred seventy-eight thousand, eight hundred sixty-one".