1291789 has 4 divisors (see below), whose sum is σ = 1297660. Its totient is φ = 1285920.

The previous prime is 1291783. The next prime is 1291793. The reversal of 1291789 is 9871921.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9871921 = 181 ⋅54541.

It can be written as a sum of positive squares in 2 ways, for example, as 1247689 + 44100 = 1117^2 + 210^2 .

It is a cyclic number.

It is not a de Polignac number, because 1291789 - 2¹⁷ = 1160717 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1291783) 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, 2592 + ... + 3049.

It is an arithmetic number, because the mean of its divisors is an integer number (324415).

2^1291789 is an apocalyptic number.

It is an amenable number.

1291789 is a deficient number, since it is larger than the sum of its proper divisors (5871).

1291789 is an equidigital number, since it uses as much as digits as its factorization.

1291789 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5870.

The product of its digits is 9072, while the sum is 37.

The square root of 1291789 is about 1136.5689596325. The cubic root of 1291789 is about 108.9090226472.

It can be divided in two parts, 1291 and 789, that added together give a triangular number (2080 = T₆₄).

The spelling of 1291789 in words is "one million, two hundred ninety-one thousand, seven hundred eighty-nine".