721403 has 4 divisors (see below), whose sum is σ = 736800. Its totient is φ = 706008.

The previous prime is 721397. The next prime is 721439. The reversal of 721403 is 304127.

It is a happy number.

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

It is a cyclic number.

It is not a de Polignac number, because 721403 - 2⁴ = 721387 is a prime.

It is an Ulam number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (721003) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 7628 + ... + 7721.

It is an arithmetic number, because the mean of its divisors is an integer number (184200).

2⁷²¹⁴⁰³ is an apocalyptic number.

721403 is a deficient number, since it is larger than the sum of its proper divisors (15397).

721403 is a wasteful number, since it uses less digits than its factorization.

721403 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15396.

The product of its (nonzero) digits is 168, while the sum is 17.

The square root of 721403 is about 849.3544607524. The cubic root of 721403 is about 89.6862739253.

The spelling of 721403 in words is "seven hundred twenty-one thousand, four hundred three", and thus it is an iban number.