291997 has 2 divisors, whose sum is σ = 291998. Its totient is φ = 291996.

The previous prime is 291983. The next prime is 292021. The reversal of 291997 is 799192.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 244036 + 47961 = 494^2 + 219^2 .

291997 is a truncatable prime.

It is a cyclic number.

It is not a de Polignac number, because 291997 - 2⁷ = 291869 is a prime.

291997 is a lucky number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (294997) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 145998 + 145999.

It is an arithmetic number, because the mean of its divisors is an integer number (145999).

2²⁹¹⁹⁹⁷ is an apocalyptic number.

It is an amenable number.

291997 is a deficient number, since it is larger than the sum of its proper divisors (1).

291997 is an equidigital number, since it uses as much as digits as its factorization.

291997 is an evil number, because the sum of its binary digits is even.

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

The square root of 291997 is about 540.3674675626. The cubic root of 291997 is about 66.3426471663.

Adding to 291997 its product of digits (10206), we get a palindrome (302203).

The spelling of 291997 in words is "two hundred ninety-one thousand, nine hundred ninety-seven".