721717220 has 48 divisors (see below), whose sum is σ = 1742549760. Its totient is φ = 245956224.

The previous prime is 721717159. The next prime is 721717237. The reversal of 721717220 is 22717127.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 7946 + ... + 38814.

It is an arithmetic number, because the mean of its divisors is an integer number (36303120).

Almost surely, 2^721717220 is an apocalyptic number.

721717220 is a gapful number since it is divisible by the number (70) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 721717220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (871274880).

721717220 is an abundant number, since it is smaller than the sum of its proper divisors (1020832540).

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

721717220 is a wasteful number, since it uses less digits than its factorization.

721717220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31052 (or 31050 counting only the distinct ones).

The product of its (nonzero) digits is 2744, while the sum is 29.

The square root of 721717220 is about 26864.7951788209. The cubic root of 721717220 is about 896.9929352293.

The spelling of 721717220 in words is "seven hundred twenty-one million, seven hundred seventeen thousand, two hundred twenty".