1891081 has 4 divisors (see below), whose sum is σ = 1893892. Its totient is φ = 1888272.

The previous prime is 1891073. The next prime is 1891103. The reversal of 1891081 is 1801981.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 1801981 = 23 ⋅78347.

It can be written as a sum of positive squares in 2 ways, for example, as 341056 + 1550025 = 584^2 + 1245^2 .

It is a cyclic number.

It is not a de Polignac number, because 1891081 - 2³ = 1891073 is a prime.

It is a super-2 number, since 2×1891081² = 7152374697122, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1891381) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 271 + ... + 1963.

It is an arithmetic number, because the mean of its divisors is an integer number (473473).

2^1891081 is an apocalyptic number.

It is an amenable number.

1891081 is a deficient number, since it is larger than the sum of its proper divisors (2811).

1891081 is a wasteful number, since it uses less digits than its factorization.

1891081 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2810.

The product of its (nonzero) digits is 576, while the sum is 28.

The square root of 1891081 is about 1375.1658081846. The cubic root of 1891081 is about 123.6621265091.

The spelling of 1891081 in words is "one million, eight hundred ninety-one thousand, eighty-one".