721523 has 12 divisors (see below), whose sum is σ = 813960. Its totient is φ = 638880.

The previous prime is 721499. The next prime is 721529. The reversal of 721523 is 325127.

It is not a de Polignac number, because 721523 - 2⁸ = 721267 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 721495 and 721504.

It is not an unprimeable number, because it can be changed into a prime (721529) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 8063 + ... + 8151.

It is an arithmetic number, because the mean of its divisors is an integer number (67830).

2⁷²¹⁵²³ is an apocalyptic number.

721523 is a deficient number, since it is larger than the sum of its proper divisors (92437).

721523 is a wasteful number, since it uses less digits than its factorization.

721523 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 178 (or 167 counting only the distinct ones).

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

The square root of 721523 is about 849.4250996998. The cubic root of 721523 is about 89.6912465302.

The spelling of 721523 in words is "seven hundred twenty-one thousand, five hundred twenty-three".