1966991 has 12 divisors (see below), whose sum is σ = 2169648. Its totient is φ = 1782144.

The previous prime is 1966973. The next prime is 1966999. The reversal of 1966991 is 1996691.

It is not a de Polignac number, because 1966991 - 2¹⁰ = 1965967 is a prime.

It is a zygodrome in base 2.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1966999) 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 11 ways as a sum of consecutive naturals, for example, 17351 + ... + 17463.

It is an arithmetic number, because the mean of its divisors is an integer number (180804).

2^1966991 is an apocalyptic number.

1966991 is a deficient number, since it is larger than the sum of its proper divisors (202657).

1966991 is a wasteful number, since it uses less digits than its factorization.

1966991 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 242 (or 229 counting only the distinct ones).

The product of its digits is 26244, while the sum is 41.

The square root of 1966991 is about 1402.4945632693. The cubic root of 1966991 is about 125.2951107290.

The spelling of 1966991 in words is "one million, nine hundred sixty-six thousand, nine hundred ninety-one".