1966891 has 4 divisors (see below), whose sum is σ = 2052432. Its totient is φ = 1881352.

The previous prime is 1966889. The next prime is 1966897. The reversal of 1966891 is 1986691.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1986691 = 7 ⋅283813.

It is a cyclic number.

It is not a de Polignac number, because 1966891 - 2¹ = 1966889 is a prime.

It is a Duffinian number.

1966891 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (1966897) 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, 42736 + ... + 42781.

It is an arithmetic number, because the mean of its divisors is an integer number (513108).

2^1966891 is an apocalyptic number.

1966891 is a deficient number, since it is larger than the sum of its proper divisors (85541).

1966891 is an equidigital number, since it uses as much as digits as its factorization.

1966891 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 85540.

The product of its digits is 23328, while the sum is 40.

The square root of 1966891 is about 1402.4589120541. The cubic root of 1966891 is about 125.2929873972.

The spelling of 1966891 in words is "one million, nine hundred sixty-six thousand, eight hundred ninety-one".