1691997 has 4 divisors (see below), whose sum is σ = 2256000. Its totient is φ = 1127996.

The previous prime is 1691983. The next prime is 1692013. The reversal of 1691997 is 7991961.

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.

It is a cyclic number.

It is not a de Polignac number, because 1691997 - 2⁶ = 1691933 is a prime.

It is a D-number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1691917) 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, 281997 + ... + 282002.

It is an arithmetic number, because the mean of its divisors is an integer number (564000).

2^1691997 is an apocalyptic number.

It is an amenable number.

1691997 is a deficient number, since it is larger than the sum of its proper divisors (564003).

1691997 is an equidigital number, since it uses as much as digits as its factorization.

1691997 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 564002.

The product of its digits is 30618, while the sum is 42.

The square root of 1691997 is about 1300.7678501562. The cubic root of 1691997 is about 119.1607412793.

The spelling of 1691997 in words is "one million, six hundred ninety-one thousand, nine hundred ninety-seven".