1997689 has 4 divisors (see below), whose sum is σ = 2030500. Its totient is φ = 1964880.

The previous prime is 1997683. The next prime is 1997693. The reversal of 1997689 is 9867991.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 9867991 = 7 ⋅1409713.

It can be written as a sum of positive squares in 2 ways, for example, as 242064 + 1755625 = 492^2 + 1325^2 .

It is a cyclic number.

It is not a de Polignac number, because 1997689 - 2⁵ = 1997657 is a prime.

It is a super-2 number, since 2×1997689² = 7981522681442, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1997683) 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, 16314 + ... + 16435.

It is an arithmetic number, because the mean of its divisors is an integer number (507625).

2^1997689 is an apocalyptic number.

It is an amenable number.

1997689 is a deficient number, since it is larger than the sum of its proper divisors (32811).

1997689 is an equidigital number, since it uses as much as digits as its factorization.

1997689 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 32810.

The product of its digits is 244944, while the sum is 49.

The square root of 1997689 is about 1413.3962643222. The cubic root of 1997689 is about 125.9435583270.

The spelling of 1997689 in words is "one million, nine hundred ninety-seven thousand, six hundred eighty-nine".