691920 has 90 divisors (see below), whose sum is σ = 2401074. Its totient is φ = 178560.

The previous prime is 691919. The next prime is 691921. The reversal of 691920 is 29196.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (691919) and next prime (691921).

It can be written as a sum of positive squares in only one way, i.e., 553536 + 138384 = 744^2 + 372^2 .

It is a tau number, because it is divible by the number of its divisors (90).

It is a Smith number, since the sum of its digits (27) coincides with the sum of the digits of its prime factors.

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 691920.

It is not an unprimeable number, because it can be changed into a prime (691921) by changing a digit.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 22305 + ... + 22335.

2⁶⁹¹⁹²⁰ is an apocalyptic number.

691920 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 691920, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1200537).

691920 is an abundant number, since it is smaller than the sum of its proper divisors (1709154).

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

691920 is a wasteful number, since it uses less digits than its factorization.

691920 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 81 (or 41 counting only the distinct ones).

The product of its (nonzero) digits is 972, while the sum is 27.

The square root of 691920 is about 831.8172876299. The cubic root of 691920 is about 88.4474455762.

The spelling of 691920 in words is "six hundred ninety-one thousand, nine hundred twenty".