721489 has 4 divisors (see below), whose sum is σ = 735156. Its totient is φ = 707824.

The previous prime is 721481. The next prime is 721499. The reversal of 721489 is 984127.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 173889 + 547600 = 417^2 + 740^2 .

It is a cyclic number.

It is not a de Polignac number, because 721489 - 2³ = 721481 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 721489.

It is not an unprimeable number, because it can be changed into a prime (721481) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6754 + ... + 6859.

It is an arithmetic number, because the mean of its divisors is an integer number (183789).

2⁷²¹⁴⁸⁹ is an apocalyptic number.

It is an amenable number.

721489 is a deficient number, since it is larger than the sum of its proper divisors (13667).

721489 is a wasteful number, since it uses less digits than its factorization.

721489 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13666.

The product of its digits is 4032, while the sum is 31.

The square root of 721489 is about 849.4050859278. The cubic root of 721489 is about 89.6898376814.

The spelling of 721489 in words is "seven hundred twenty-one thousand, four hundred eighty-nine".