691660 has 12 divisors (see below), whose sum is σ = 1452528. Its totient is φ = 276656.

The previous prime is 691651. The next prime is 691661. The reversal of 691660 is 66196.

It is a happy number.

691660 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not an unprimeable number, because it can be changed into a prime (691661) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 17272 + ... + 17311.

It is an arithmetic number, because the mean of its divisors is an integer number (121044).

2⁶⁹¹⁶⁶⁰ is an apocalyptic number.

It is an amenable number.

691660 is an abundant number, since it is smaller than the sum of its proper divisors (760868).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

691660 is a wasteful number, since it uses less digits than its factorization.

691660 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34592 (or 34590 counting only the distinct ones).

The product of its (nonzero) digits is 1944, while the sum is 28.

The square root of 691660 is about 831.6609886246. The cubic root of 691660 is about 88.4363656745.

The spelling of 691660 in words is "six hundred ninety-one thousand, six hundred sixty".