691691 has 16 divisors (see below), whose sum is σ = 930048. Its totient is φ = 496800.

The previous prime is 691687. The next prime is 691693. The reversal of 691691 is 196196.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 691691 - 2² = 691687 is a prime.

It is an Ulam number.

It is not an unprimeable number, because it can be changed into a prime (691693) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 656 + ... + 1346.

It is an arithmetic number, because the mean of its divisors is an integer number (58128).

2⁶⁹¹⁶⁹¹ is an apocalyptic number.

691691 is a deficient number, since it is larger than the sum of its proper divisors (238357).

691691 is a wasteful number, since it uses less digits than its factorization.

691691 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 722.

The product of its digits is 2916, while the sum is 32.

The square root of 691691 is about 831.6796258175. The cubic root of 691691 is about 88.4376868854.

It can be divided in two parts, 6916 and 91, that added together give a palindrome (7007).

The spelling of 691691 in words is "six hundred ninety-one thousand, six hundred ninety-one".