1991061 has 20 divisors (see below), whose sum is σ = 3043392. Its totient is φ = 1296648.

The previous prime is 1991047. The next prime is 1991063. The reversal of 1991061 is 1601991.

It is a de Polignac number, because none of the positive numbers 2^k-1991061 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a Curzon number.

1991061 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1991063) 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 19 ways as a sum of consecutive naturals, for example, 3546 + ... + 4068.

2^1991061 is an apocalyptic number.

It is an amenable number.

1991061 is a deficient number, since it is larger than the sum of its proper divisors (1052331).

1991061 is an equidigital number, since it uses as much as digits as its factorization.

1991061 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 582 (or 573 counting only the distinct ones).

The product of its (nonzero) digits is 486, while the sum is 27.

The square root of 1991061 is about 1411.0496093334. The cubic root of 1991061 is about 125.8041174028.

The spelling of 1991061 in words is "one million, nine hundred ninety-one thousand, sixty-one".