691841 has 2 divisors, whose sum is σ = 691842. Its totient is φ = 691840.

The previous prime is 691837. The next prime is 691843. The reversal of 691841 is 148196.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 462400 + 229441 = 680^2 + 479^2 .

It is a cyclic number.

It is not a de Polignac number, because 691841 - 2² = 691837 is a prime.

Together with 691843, it forms a pair of twin primes.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (691843) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 345920 + 345921.

It is an arithmetic number, because the mean of its divisors is an integer number (345921).

2⁶⁹¹⁸⁴¹ is an apocalyptic number.

It is an amenable number.

691841 is a deficient number, since it is larger than the sum of its proper divisors (1).

691841 is an equidigital number, since it uses as much as digits as its factorization.

691841 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1728, while the sum is 29.

The square root of 691841 is about 831.7697998846. The cubic root of 691841 is about 88.4440792843. Note that the first 3 decimals are identical.

The spelling of 691841 in words is "six hundred ninety-one thousand, eight hundred forty-one".