691091 has 4 divisors (see below), whose sum is σ = 700632. Its totient is φ = 681552.

The previous prime is 691079. The next prime is 691109. The reversal of 691091 is 190196.

691091 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-691091 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 691091.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 691091.

It is not an unprimeable number, because it can be changed into a prime (691001) 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, 4661 + ... + 4806.

It is an arithmetic number, because the mean of its divisors is an integer number (175158).

2⁶⁹¹⁰⁹¹ is an apocalyptic number.

691091 is a deficient number, since it is larger than the sum of its proper divisors (9541).

691091 is an equidigital number, since it uses as much as digits as its factorization.

691091 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9540.

The product of its (nonzero) digits is 486, while the sum is 26.

The square root of 691091 is about 831.3188317367. The cubic root of 691091 is about 88.4121080444.

The spelling of 691091 in words is "six hundred ninety-one thousand, ninety-one".