291689 has 2 divisors, whose sum is σ = 291690. Its totient is φ = 291688.

The previous prime is 291677. The next prime is 291691. The reversal of 291689 is 986192.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 211600 + 80089 = 460^2 + 283^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-291689 is a prime.

Together with 291691, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (291619) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 145844 + 145845.

It is an arithmetic number, because the mean of its divisors is an integer number (145845).

2²⁹¹⁶⁸⁹ is an apocalyptic number.

It is an amenable number.

291689 is a deficient number, since it is larger than the sum of its proper divisors (1).

291689 is an equidigital number, since it uses as much as digits as its factorization.

291689 is an evil number, because the sum of its binary digits is even.

The product of its digits is 7776, while the sum is 35.

The square root of 291689 is about 540.0824011204. The cubic root of 291689 is about 66.3193127667.

The spelling of 291689 in words is "two hundred ninety-one thousand, six hundred eighty-nine".