7971840 has 132 divisors (see below), whose sum is σ = 27781884. Its totient is φ = 2113536.

The previous prime is 7971833. The next prime is 7971851. The reversal of 7971840 is 481797.

It can be written as a sum of positive squares in 2 ways, for example, as 5308416 + 2663424 = 2304^2 + 1632^2 .

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 = 7971795 and 7971804.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 45994 + ... + 46166.

Almost surely, 2^7971840 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 7971840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (13890942).

7971840 is an abundant number, since it is smaller than the sum of its proper divisors (19810044).

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

7971840 is a wasteful number, since it uses less digits than its factorization.

7971840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 204 (or 183 counting only the distinct ones).

The product of its (nonzero) digits is 14112, while the sum is 36.

The square root of 7971840 is about 2823.4447046117. Note that the first 3 decimals coincide. The cubic root of 7971840 is about 199.7650574514.

The spelling of 7971840 in words is "seven million, nine hundred seventy-one thousand, eight hundred forty".