721753 has 4 divisors (see below), whose sum is σ = 759760. Its totient is φ = 683748.

The previous prime is 721739. The next prime is 721783. The reversal of 721753 is 357127.

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, and also an emirpimes, since its reverse is a distinct semiprime: 357127 = 59 ⋅6053.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-721753 is a prime.

It is a Duffinian number.

721753 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (721703) 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, 18975 + ... + 19012.

It is an arithmetic number, because the mean of its divisors is an integer number (189940).

2⁷²¹⁷⁵³ is an apocalyptic number.

It is an amenable number.

721753 is a deficient number, since it is larger than the sum of its proper divisors (38007).

721753 is a wasteful number, since it uses less digits than its factorization.

721753 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38006.

The product of its digits is 1470, while the sum is 25.

The square root of 721753 is about 849.5604745985. The cubic root of 721753 is about 89.7007758153.

The spelling of 721753 in words is "seven hundred twenty-one thousand, seven hundred fifty-three".