691231 has 2 divisors, whose sum is σ = 691232. Its totient is φ = 691230.

The previous prime is 691199. The next prime is 691241. The reversal of 691231 is 132196.

691231 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 691231 - 2⁵ = 691199 is a prime.

It is a super-2 number, since 2×691231² = 955600590722, which contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (691241) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 345615 + 345616.

It is an arithmetic number, because the mean of its divisors is an integer number (345616).

2⁶⁹¹²³¹ is an apocalyptic number.

691231 is a deficient number, since it is larger than the sum of its proper divisors (1).

691231 is an equidigital number, since it uses as much as digits as its factorization.

691231 is an evil number, because the sum of its binary digits is even.

The product of its digits is 324, while the sum is 22.

The square root of 691231 is about 831.4030310265. The cubic root of 691231 is about 88.4180777645.

The spelling of 691231 in words is "six hundred ninety-one thousand, two hundred thirty-one".