691740 has 120 divisors (see below), whose sum is σ = 2520672. Its totient is φ = 155520.

The previous prime is 691739. The next prime is 691759. The reversal of 691740 is 47196.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 11310 + ... + 11370.

2⁶⁹¹⁷⁴⁰ is an apocalyptic number.

691740 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 691740, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1260336).

691740 is an abundant number, since it is smaller than the sum of its proper divisors (1828932).

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

691740 is a wasteful number, since it uses less digits than its factorization.

691740 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 89 (or 78 counting only the distinct ones).

The product of its (nonzero) digits is 1512, while the sum is 27.

The square root of 691740 is about 831.7090837547. The cubic root of 691740 is about 88.4397751707.

It can be divided in two parts, 691 and 740, that added together give a triangular number (1431 = T₅₃).

The spelling of 691740 in words is "six hundred ninety-one thousand, seven hundred forty".