691040 has 48 divisors (see below), whose sum is σ = 1868832. Its totient is φ = 236544.

The previous prime is 691037. The next prime is 691051. The reversal of 691040 is 40196.

It is a Harshad number since it is a multiple of its sum of digits (20).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 812 + ... + 1428.

It is an arithmetic number, because the mean of its divisors is an integer number (38934).

2⁶⁹¹⁰⁴⁰ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 691040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (934416).

691040 is an abundant number, since it is smaller than the sum of its proper divisors (1177792).

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

691040 is a wasteful number, since it uses less digits than its factorization.

691040 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 639 (or 631 counting only the distinct ones).

The product of its (nonzero) digits is 216, while the sum is 20.

The square root of 691040 is about 831.2881570190. The cubic root of 691040 is about 88.4099331603.

The spelling of 691040 in words is "six hundred ninety-one thousand, forty".