723521 has 8 divisors (see below), whose sum is σ = 762600. Its totient is φ = 685440.

The previous prime is 723493. The next prime is 723529. The reversal of 723521 is 125327.

723521 = T₈₃ + T₈₄ + ... + T₁₆₉.

It can be written as a sum of positive squares in 4 ways, for example, as 83521 + 640000 = 289^2 + 800^2 .

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-723521 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 723493 and 723502.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (723529) 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, 1565 + ... + 1973.

It is an arithmetic number, because the mean of its divisors is an integer number (95325).

2⁷²³⁵²¹ is an apocalyptic number.

It is an amenable number.

723521 is a deficient number, since it is larger than the sum of its proper divisors (39079).

723521 is a wasteful number, since it uses less digits than its factorization.

723521 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 499.

The product of its digits is 420, while the sum is 20.

The square root of 723521 is about 850.6003762049. The cubic root of 723521 is about 89.7739595098.

Adding to 723521 its reverse (125327), we get a palindrome (848848).

The spelling of 723521 in words is "seven hundred twenty-three thousand, five hundred twenty-one".