1891091 has 4 divisors (see below), whose sum is σ = 1901184. Its totient is φ = 1881000.

The previous prime is 1891073. The next prime is 1891103. The reversal of 1891091 is 1901981.

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 1891091 - 2⁶ = 1891027 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1891291) 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, 4760 + ... + 5141.

It is an arithmetic number, because the mean of its divisors is an integer number (475296).

2^1891091 is an apocalyptic number.

1891091 is a deficient number, since it is larger than the sum of its proper divisors (10093).

1891091 is an equidigital number, since it uses as much as digits as its factorization.

1891091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10092.

The product of its (nonzero) digits is 648, while the sum is 29.

The square root of 1891091 is about 1375.1694441050. The cubic root of 1891091 is about 123.6623444830.

The spelling of 1891091 in words is "one million, eight hundred ninety-one thousand, ninety-one".