691679 has 16 divisors (see below), whose sum is σ = 803520. Its totient is φ = 591360.

The previous prime is 691661. The next prime is 691681. The reversal of 691679 is 976196.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-691679 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (691079) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 11309 + ... + 11369.

It is an arithmetic number, because the mean of its divisors is an integer number (50220).

2⁶⁹¹⁶⁷⁹ is an apocalyptic number.

691679 is a deficient number, since it is larger than the sum of its proper divisors (111841).

691679 is a wasteful number, since it uses less digits than its factorization.

691679 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 130.

The product of its digits is 20412, while the sum is 38.

The square root of 691679 is about 831.6724114698. The cubic root of 691679 is about 88.4371754536.

The spelling of 691679 in words is "six hundred ninety-one thousand, six hundred seventy-nine".