7981891 has 12 divisors (see below), whose sum is σ = 8620560. Its totient is φ = 7387520.

The previous prime is 7981889. The next prime is 7981907. The reversal of 7981891 is 1981897.

It is not a de Polignac number, because 7981891 - 2¹ = 7981889 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (7981801) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 20325 + ... + 20713.

It is an arithmetic number, because the mean of its divisors is an integer number (718380).

Almost surely, 2^7981891 is an apocalyptic number.

7981891 is a gapful number since it is divisible by the number (71) formed by its first and last digit.

7981891 is a deficient number, since it is larger than the sum of its proper divisors (638669).

7981891 is a wasteful number, since it uses less digits than its factorization.

7981891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 494 (or 477 counting only the distinct ones).

The product of its digits is 36288, while the sum is 43.

The square root of 7981891 is about 2825.2240619108. The cubic root of 7981891 is about 199.8489776566.

The spelling of 7981891 in words is "seven million, nine hundred eighty-one thousand, eight hundred ninety-one".