721591 has 8 divisors (see below), whose sum is σ = 794304. Its totient is φ = 651360.

The previous prime is 721577. The next prime is 721597. The reversal of 721591 is 195127.

721591 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 721591 - 2⁹ = 721079 is a prime.

It is a Duffinian number.

721591 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721597) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 21 + ... + 1201.

It is an arithmetic number, because the mean of its divisors is an integer number (99288).

2⁷²¹⁵⁹¹ is an apocalyptic number.

721591 is a deficient number, since it is larger than the sum of its proper divisors (72713).

721591 is a wasteful number, since it uses less digits than its factorization.

721591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1241.

The product of its digits is 630, while the sum is 25.

The square root of 721591 is about 849.4651258292. The cubic root of 721591 is about 89.6940640948.

The spelling of 721591 in words is "seven hundred twenty-one thousand, five hundred ninety-one".