721313 has 8 divisors (see below), whose sum is σ = 752136. Its totient is φ = 691200.

The previous prime is 721307. The next prime is 721319. The reversal of 721313 is 313127.

It is an interprime number because it is at equal distance from previous prime (721307) and next prime (721319).

It can be written as a sum of positive squares in 4 ways, for example, as 53824 + 667489 = 232^2 + 817^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 721313 - 2⁸ = 721057 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 721291 and 721300.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 721313.

It is not an unprimeable number, because it can be changed into a prime (721319) 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 7 ways as a sum of consecutive naturals, for example, 2873 + ... + 3113.

It is an arithmetic number, because the mean of its divisors is an integer number (94017).

2⁷²¹³¹³ is an apocalyptic number.

721313 is a gapful number since it is divisible by the number (73) formed by its first and last digit.

It is an amenable number.

721313 is a deficient number, since it is larger than the sum of its proper divisors (30823).

721313 is a wasteful number, since it uses less digits than its factorization.

721313 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 355.

The product of its digits is 126, while the sum is 17.

The square root of 721313 is about 849.3014776862. The cubic root of 721313 is about 89.6825441098.

The spelling of 721313 in words is "seven hundred twenty-one thousand, three hundred thirteen".