721215840 has 96 divisors (see below), whose sum is σ = 2333288160. Its totient is φ = 187121664.

The previous prime is 721215827. The next prime is 721215841. The reversal of 721215840 is 48512127.

721215840 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a tau number, because it is divible by the number of its divisors (96).

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a junction number, because it is equal to n+sod(n) for n = 721215798 and 721215807.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721215841) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2545 + ... + 38064.

It is an arithmetic number, because the mean of its divisors is an integer number (24305085).

Almost surely, 2^721215840 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 721215840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1166644080).

721215840 is an abundant number, since it is smaller than the sum of its proper divisors (1612072320).

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

721215840 is a wasteful number, since it uses less digits than its factorization.

721215840 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40664 (or 40656 counting only the distinct ones).

The product of its (nonzero) digits is 4480, while the sum is 30.

The square root of 721215840 is about 26855.4620142719. The cubic root of 721215840 is about 896.7851721841.

Adding to 721215840 its reverse (48512127), we get a palindrome (769727967).

The spelling of 721215840 in words is "seven hundred twenty-one million, two hundred fifteen thousand, eight hundred forty".