7840991 has 4 divisors (see below), whose sum is σ = 8111400. Its totient is φ = 7570584.

The previous prime is 7840981. The next prime is 7840997. The reversal of 7840991 is 1990487.

7840991 is digitally balanced in base 3, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-7840991 is a prime.

It is a super-2 number, since 2×7840991² = 122962279724162, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7840997) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 135161 + ... + 135218.

It is an arithmetic number, because the mean of its divisors is an integer number (2027850).

Almost surely, 2^7840991 is an apocalyptic number.

7840991 is a deficient number, since it is larger than the sum of its proper divisors (270409).

7840991 is a wasteful number, since it uses less digits than its factorization.

7840991 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 270408.

The product of its (nonzero) digits is 18144, while the sum is 38.

The square root of 7840991 is about 2800.1769586939. The cubic root of 7840991 is about 198.6660476361. Note that the first 3 decimals are identical.

The spelling of 7840991 in words is "seven million, eight hundred forty thousand, nine hundred ninety-one".