691009 has 4 divisors (see below), whose sum is σ = 753840. Its totient is φ = 628180.

The previous prime is 691001. The next prime is 691037. The reversal of 691009 is 900196.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 691009 - 2³ = 691001 is a prime.

It is an Ulam number.

It is a Duffinian number.

691009 is a lucky number.

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, 31399 + ... + 31420.

It is an arithmetic number, because the mean of its divisors is an integer number (188460).

2⁶⁹¹⁰⁰⁹ is an apocalyptic number.

It is an amenable number.

691009 is a deficient number, since it is larger than the sum of its proper divisors (62831).

691009 is a wasteful number, since it uses less digits than its factorization.

691009 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 62830.

The product of its (nonzero) digits is 486, while the sum is 25.

The square root of 691009 is about 831.2695110492. The cubic root of 691009 is about 88.4086111197.

The spelling of 691009 in words is "six hundred ninety-one thousand, nine".