7881391 has 4 divisors (see below), whose sum is σ = 9007312. Its totient is φ = 6755472.

The previous prime is 7881373. The next prime is 7881487. The reversal of 7881391 is 1931887.

7881391 is digitally balanced in base 8, 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 not a de Polignac number, because 7881391 - 2⁹ = 7880879 is a prime.

It is a Duffinian number.

7881391 is strictly pandigital in base 8.

It is a self number, because there is not a number n which added to its sum of digits gives 7881391.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (7881331) 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, 562950 + ... + 562963.

It is an arithmetic number, because the mean of its divisors is an integer number (2251828).

Almost surely, 2^7881391 is an apocalyptic number.

7881391 is a deficient number, since it is larger than the sum of its proper divisors (1125921).

7881391 is a wasteful number, since it uses less digits than its factorization.

7881391 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1125920.

The product of its digits is 12096, while the sum is 37.

The square root of 7881391 is about 2807.3815202070. The cubic root of 7881391 is about 199.0066662750.

It can be divided in two parts, 788139 and 1, that added together give a triangular number (788140 = T₁₂₅₅).

The spelling of 7881391 in words is "seven million, eight hundred eighty-one thousand, three hundred ninety-one".