1918891 has 4 divisors (see below), whose sum is σ = 2066512. Its totient is φ = 1771272.

The previous prime is 1918879. The next prime is 1918897. The reversal of 1918891 is 1988191.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1988191 = 43 ⋅46237.

It is a cyclic number.

It is not a de Polignac number, because 1918891 - 2⁵ = 1918859 is a prime.

It is a Duffinian number.

1918891 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 1918891.

It is not an unprimeable number, because it can be changed into a prime (1918897) 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 3 ways as a sum of consecutive naturals, for example, 73791 + ... + 73816.

It is an arithmetic number, because the mean of its divisors is an integer number (516628).

2^1918891 is an apocalyptic number.

1918891 is a deficient number, since it is larger than the sum of its proper divisors (147621).

1918891 is a wasteful number, since it uses less digits than its factorization.

1918891 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 147620.

The product of its digits is 5184, while the sum is 37.

The square root of 1918891 is about 1385.2404123473. The cubic root of 1918891 is about 124.2653656234.

It can be divided in two parts, 191889 and 1, that added together give a triangular number (191890 = T₆₁₉).

The spelling of 1918891 in words is "one million, nine hundred eighteen thousand, eight hundred ninety-one".