721728224 has 192 divisors, whose sum is σ = 1826012160. Its totient is φ = 273715200.

The previous prime is 721728223. The next prime is 721728257. The reversal of 721728224 is 422827127.

It is a Cunningham number, because it is equal to 26865²-1.

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721728223) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 7145774 + ... + 7145874.

It is an arithmetic number, because the mean of its divisors is an integer number (9510480).

Almost surely, 2^721728224 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 721728224, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (913006080).

721728224 is an abundant number, since it is smaller than the sum of its proper divisors (1104283936).

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

721728224 is a wasteful number, since it uses less digits than its factorization.

721728224 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 233 (or 225 counting only the distinct ones).

The product of its digits is 25088, while the sum is 35.

The square root of 721728224 is about 26864.9999813884. Note that the first 4 decimals coincide. The cubic root of 721728224 is about 896.9974940139.

The spelling of 721728224 in words is "seven hundred twenty-one million, seven hundred twenty-eight thousand, two hundred twenty-four".