721824 has 48 divisors (see below), whose sum is σ = 1939392. Its totient is φ = 235008.

The previous prime is 721793. The next prime is 721843. The reversal of 721824 is 428127.

721824 is nontrivially palindromic in base 11.

It is a tau number, because it is divible by the number of its divisors (48).

It is a Harshad number since it is a multiple of its sum of digits (24).

It is a junction number, because it is equal to n+sod(n) for n = 721794 and 721803.

It is an unprimeable number.

721824 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

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, 6957 + ... + 7059.

It is an arithmetic number, because the mean of its divisors is an integer number (40404).

2⁷²¹⁸²⁴ 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 721824, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (969696).

721824 is an abundant number, since it is smaller than the sum of its proper divisors (1217568).

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

721824 is a wasteful number, since it uses less digits than its factorization.

721824 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 189 (or 181 counting only the distinct ones).

The product of its digits is 896, while the sum is 24.

The square root of 721824 is about 849.6022598840. The cubic root of 721824 is about 89.7037170552.

It can be divided in two parts, 72 and 1824, that multiplied together give a triangular number (131328 = T₅₁₂).

The spelling of 721824 in words is "seven hundred twenty-one thousand, eight hundred twenty-four".