721393 has 4 divisors (see below), whose sum is σ = 733680. Its totient is φ = 709108.

The previous prime is 721387. The next prime is 721397. The reversal of 721393 is 393127.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 721393 - 2¹⁷ = 590321 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (721397) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 6055 + ... + 6172.

It is an arithmetic number, because the mean of its divisors is an integer number (183420).

2⁷²¹³⁹³ is an apocalyptic number.

It is an amenable number.

721393 is a deficient number, since it is larger than the sum of its proper divisors (12287).

721393 is a wasteful number, since it uses less digits than its factorization.

721393 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12286.

The product of its digits is 1134, while the sum is 25.

The square root of 721393 is about 849.3485739083. The cubic root of 721393 is about 89.6858595167.

The spelling of 721393 in words is "seven hundred twenty-one thousand, three hundred ninety-three".