721108 has 12 divisors (see below), whose sum is σ = 1293012. Its totient is φ = 351680.

The previous prime is 721087. The next prime is 721109. The reversal of 721108 is 801127.

It can be written as a sum of positive squares in 2 ways, for example, as 161604 + 559504 = 402^2 + 748^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (721109) by changing a digit.

721108 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 3 ways as a sum of consecutive naturals, for example, 2035 + ... + 2362.

It is an arithmetic number, because the mean of its divisors is an integer number (107751).

2⁷²¹¹⁰⁸ is an apocalyptic number.

It is an amenable number.

721108 is a deficient number, since it is larger than the sum of its proper divisors (571904).

721108 is a wasteful number, since it uses less digits than its factorization.

721108 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4442 (or 4440 counting only the distinct ones).

The product of its (nonzero) digits is 112, while the sum is 19.

The square root of 721108 is about 849.1807816949. The cubic root of 721108 is about 89.6740472605.

Adding to 721108 its sum of digits (19), we get a palindrome (721127).

It can be divided in two parts, 7 and 21108, that added together give a triangular number (21115 = T₂₀₅).

The spelling of 721108 in words is "seven hundred twenty-one thousand, one hundred eight".