1997209 has 4 divisors (see below), whose sum is σ = 2031120. Its totient is φ = 1963300.

The previous prime is 1997189. The next prime is 1997213. The reversal of 1997209 is 9027991.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 9027991 = 7 ⋅1289713.

It is a cyclic number.

It is not a de Polignac number, because 1997209 - 2⁷ = 1997081 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (1997269) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 16867 + ... + 16984.

It is an arithmetic number, because the mean of its divisors is an integer number (507780).

2^1997209 is an apocalyptic number.

It is an amenable number.

1997209 is a deficient number, since it is larger than the sum of its proper divisors (33911).

1997209 is an equidigital number, since it uses as much as digits as its factorization.

1997209 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 33910.

The product of its (nonzero) digits is 10206, while the sum is 37.

The square root of 1997209 is about 1413.2264503610. The cubic root of 1997209 is about 125.9334703787.

The spelling of 1997209 in words is "one million, nine hundred ninety-seven thousand, two hundred nine".