691644 has 12 divisors (see below), whose sum is σ = 1613864. Its totient is φ = 230544.

The previous prime is 691637. The next prime is 691651. The reversal of 691644 is 446196.

It is an interprime number because it is at equal distance from previous prime (691637) and next prime (691651).

It is a tau number, because it is divible by the number of its divisors (12).

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 691644.

It is an unprimeable number.

691644 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 28807 + ... + 28830.

2⁶⁹¹⁶⁴⁴ is an apocalyptic number.

It is an amenable number.

691644 is an abundant number, since it is smaller than the sum of its proper divisors (922220).

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

691644 is a wasteful number, since it uses less digits than its factorization.

691644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 57644 (or 57642 counting only the distinct ones).

The product of its digits is 5184, while the sum is 30.

The square root of 691644 is about 831.6513692648. The cubic root of 691644 is about 88.4356837437.

The spelling of 691644 in words is "six hundred ninety-one thousand, six hundred forty-four".