721530684 has 144 divisors (see below), whose sum is σ = 2159539200. Its totient is φ = 203001120.

The previous prime is 721530683. The next prime is 721530707. The reversal of 721530684 is 486035127.

721530684 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721530683) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 876297 + ... + 877119.

It is an arithmetic number, because the mean of its divisors is an integer number (14996800).

Almost surely, 2^721530684 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 721530684, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1079769600).

721530684 is an abundant number, since it is smaller than the sum of its proper divisors (1438008516).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

721530684 is a wasteful number, since it uses less digits than its factorization.

721530684 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 925 (or 906 counting only the distinct ones).

The product of its (nonzero) digits is 40320, while the sum is 36.

The square root of 721530684 is about 26861.3231989789. The cubic root of 721530684 is about 896.9156492383.

The spelling of 721530684 in words is "seven hundred twenty-one million, five hundred thirty thousand, six hundred eighty-four".