721560 has 64 divisors (see below), whose sum is σ = 2476800. Its totient is φ = 164736.

The previous prime is 721547. The next prime is 721561. The reversal of 721560 is 65127.

It is a Harshad number since it is a multiple of its sum of digits (21).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721561) by changing a digit.

721560 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 15 ways as a sum of consecutive naturals, for example, 411 + ... + 1269.

It is an arithmetic number, because the mean of its divisors is an integer number (38700).

2⁷²¹⁵⁶⁰ is an apocalyptic number.

721560 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 721560, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1238400).

721560 is an abundant number, since it is smaller than the sum of its proper divisors (1755240).

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

721560 is a wasteful number, since it uses less digits than its factorization.

721560 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 880 (or 876 counting only the distinct ones).

The product of its (nonzero) digits is 420, while the sum is 21.

The square root of 721560 is about 849.4468788571. The cubic root of 721560 is about 89.6927796388.

Adding to 721560 its reverse (65127), we get a palindrome (786687).

The spelling of 721560 in words is "seven hundred twenty-one thousand, five hundred sixty".