1997791 has 4 divisors (see below), whose sum is σ = 2025232. Its totient is φ = 1970352.

The previous prime is 1997773. The next prime is 1997813. The reversal of 1997791 is 1977991.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 1997791 - 2⁷ = 1997663 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 (1997701) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13611 + ... + 13756.

It is an arithmetic number, because the mean of its divisors is an integer number (506308).

2^1997791 is an apocalyptic number.

1997791 is a deficient number, since it is larger than the sum of its proper divisors (27441).

1997791 is an equidigital number, since it uses as much as digits as its factorization.

1997791 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27440.

The product of its digits is 35721, while the sum is 43.

The square root of 1997791 is about 1413.4323471606. The cubic root of 1997791 is about 125.9457018079.

The spelling of 1997791 in words is "one million, nine hundred ninety-seven thousand, seven hundred ninety-one".