721491 has 8 divisors (see below), whose sum is σ = 995280. Its totient is φ = 464352.

The previous prime is 721481. The next prime is 721499. The reversal of 721491 is 194127.

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

It is not a de Polignac number, because 721491 - 2⁷ = 721363 is a prime.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 721491.

It is not an unprimeable number, because it can be changed into a prime (721499) 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, 4060 + ... + 4233.

It is an arithmetic number, because the mean of its divisors is an integer number (124410).

2⁷²¹⁴⁹¹ is an apocalyptic number.

721491 is a deficient number, since it is larger than the sum of its proper divisors (273789).

721491 is a wasteful number, since it uses less digits than its factorization.

721491 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 8325.

The product of its digits is 504, while the sum is 24.

The square root of 721491 is about 849.4062632216. The cubic root of 721491 is about 89.6899205561.

The spelling of 721491 in words is "seven hundred twenty-one thousand, four hundred ninety-one".