291720 has 128 divisors (see below), whose sum is σ = 1088640. Its totient is φ = 61440.

The previous prime is 291701. The next prime is 291721. The reversal of 291720 is 27192.

It is a happy number.

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 291720.

It is not an unprimeable number, because it can be changed into a prime (291721) by changing a digit.

291720 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 17152 + ... + 17168.

It is an arithmetic number, because the mean of its divisors is an integer number (8505).

2²⁹¹⁷²⁰ is an apocalyptic number.

291720 is a gapful number since it is divisible by the number (20) 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 291720, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (544320).

291720 is an abundant number, since it is smaller than the sum of its proper divisors (796920).

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

291720 is a wasteful number, since it uses less digits than its factorization.

291720 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 55 (or 51 counting only the distinct ones).

The product of its (nonzero) digits is 252, while the sum is 21.

The square root of 291720 is about 540.1110996823. Note that the first 3 decimals coincide. The cubic root of 291720 is about 66.3216621021.

The spelling of 291720 in words is "two hundred ninety-one thousand, seven hundred twenty".