691871 has 2 divisors, whose sum is σ = 691872. Its totient is φ = 691870.

The previous prime is 691843. The next prime is 691877. The reversal of 691871 is 178196.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 691871 - 2¹⁸ = 429727 is a prime.

It is a Sophie Germain prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (691877) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 345935 + 345936.

It is an arithmetic number, because the mean of its divisors is an integer number (345936).

2⁶⁹¹⁸⁷¹ is an apocalyptic number.

691871 is a deficient number, since it is larger than the sum of its proper divisors (1).

691871 is an equidigital number, since it uses as much as digits as its factorization.

691871 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3024, while the sum is 32.

The square root of 691871 is about 831.7878335249. The cubic root of 691871 is about 88.4453576532.

The spelling of 691871 in words is "six hundred ninety-one thousand, eight hundred seventy-one".