691816 has 8 divisors (see below), whose sum is σ = 1297170. Its totient is φ = 345904.

The previous prime is 691813. The next prime is 691829. The reversal of 691816 is 618196.

It is a happy number.

It can be written as a sum of positive squares in only one way, i.e., 688900 + 2916 = 830^2 + 54^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is not an unprimeable number, because it can be changed into a prime (691813) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 43231 + ... + 43246.

2⁶⁹¹⁸¹⁶ is an apocalyptic number.

It is an amenable number.

691816 is a deficient number, since it is larger than the sum of its proper divisors (605354).

691816 is a wasteful number, since it uses less digits than its factorization.

691816 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 86483 (or 86479 counting only the distinct ones).

The product of its digits is 2592, while the sum is 31.

The square root of 691816 is about 831.7547715523. The cubic root of 691816 is about 88.4430139486.

The spelling of 691816 in words is "six hundred ninety-one thousand, eight hundred sixteen".