1997 has 2 divisors, whose sum is σ = 1998. Its totient is φ = 1996.

The previous prime is 1993. The next prime is 1999. The reversal of 1997 is 7991.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1156 + 841 = 34^2 + 29^2 .

1997 is a truncatable prime.

It is a cyclic number.

It is not a de Polignac number, because 1997 - 2² = 1993 is a prime.

Together with 1999, it forms a pair of twin primes.

It is a Chen prime.

It is a plaindrome in base 11 and base 16.

It is a nialpdrome in base 7 and base 13.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (1993) by changing a digit.

It is a good prime.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 998 + 999.

It is an arithmetic number, because the mean of its divisors is an integer number (999).

It is an amenable number.

1997 is a deficient number, since it is larger than the sum of its proper divisors (1).

1997 is an equidigital number, since it uses as much as digits as its factorization.

1997 is an evil number, because the sum of its binary digits is even.

The product of its digits is 567, while the sum is 26.

The square root of 1997 is about 44.6878059430. The cubic root of 1997 is about 12.5929077413.

The spelling of 1997 in words is "one thousand, nine hundred ninety-seven".