721329 has 16 divisors (see below), whose sum is σ = 1123200. Its totient is φ = 411600.

The previous prime is 721321. The next prime is 721333. The reversal of 721329 is 923127.

It is not a de Polignac number, because 721329 - 2³ = 721321 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 721299 and 721308.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 721329.

It is not an unprimeable number, because it can be changed into a prime (721321) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 679 + ... + 1379.

It is an arithmetic number, because the mean of its divisors is an integer number (70200).

2⁷²¹³²⁹ is an apocalyptic number.

It is an amenable number.

721329 is a deficient number, since it is larger than the sum of its proper divisors (401871).

721329 is an equidigital number, since it uses as much as digits as its factorization.

721329 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 725 (or 711 counting only the distinct ones).

The product of its digits is 756, while the sum is 24.

The square root of 721329 is about 849.3108971396. The cubic root of 721329 is about 89.6832072108.

The spelling of 721329 in words is "seven hundred twenty-one thousand, three hundred twenty-nine".