7981640 has 32 divisors (see below), whose sum is σ = 18447480. Its totient is φ = 3105792.

The previous prime is 7981639. The next prime is 7981661. The reversal of 7981640 is 461897.

It can be written as a sum of positive squares in 4 ways, for example, as 7963684 + 17956 = 2822^2 + 134^2 .

It is a self number, because there is not a number n which added to its sum of digits gives 7981640.

It is an unprimeable number.

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, 1217 + ... + 4176.

Almost surely, 2^7981640 is an apocalyptic number.

It is an amenable number.

7981640 is an abundant number, since it is smaller than the sum of its proper divisors (10465840).

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

7981640 is a wasteful number, since it uses less digits than its factorization.

7981640 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5441 (or 5437 counting only the distinct ones).

The product of its (nonzero) digits is 12096, while the sum is 35.

The square root of 7981640 is about 2825.1796403061. The cubic root of 7981640 is about 199.8468828055.

The spelling of 7981640 in words is "seven million, nine hundred eighty-one thousand, six hundred forty".