8121891 has 4 divisors (see below), whose sum is σ = 10829192. Its totient is φ = 5414592.

The previous prime is 8121889. The next prime is 8121901. The reversal of 8121891 is 1981218.

8121891 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 not a de Polignac number, because 8121891 - 2¹ = 8121889 is a prime.

It is a super-2 number, since 2×8121891² = 131930226831762, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (8121811) 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, 1353646 + ... + 1353651.

It is an arithmetic number, because the mean of its divisors is an integer number (2707298).

Almost surely, 2^8121891 is an apocalyptic number.

8121891 is a deficient number, since it is larger than the sum of its proper divisors (2707301).

8121891 is a wasteful number, since it uses less digits than its factorization.

8121891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2707300.

The product of its digits is 1152, while the sum is 30.

The square root of 8121891 is about 2849.8931558920. The cubic root of 8121891 is about 201.0106427374.

The spelling of 8121891 in words is "eight million, one hundred twenty-one thousand, eight hundred ninety-one".