721008 has 40 divisors (see below), whose sum is σ = 2070800. Its totient is φ = 240192.

The previous prime is 721003. The next prime is 721013. The reversal of 721008 is 800127.

It is an interprime number because it is at equal distance from previous prime (721003) and next prime (721013).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 721008.

It is not an unprimeable number, because it can be changed into a prime (721003) by changing a digit.

721008 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 403 + ... + 1266.

It is an arithmetic number, because the mean of its divisors is an integer number (51770).

2⁷²¹⁰⁰⁸ is an apocalyptic number.

It is an amenable number.

721008 is an abundant number, since it is smaller than the sum of its proper divisors (1349792).

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

721008 is a wasteful number, since it uses less digits than its factorization.

721008 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1686 (or 1674 counting only the distinct ones).

The product of its (nonzero) digits is 112, while the sum is 18.

The square root of 721008 is about 849.1218993761. The cubic root of 721008 is about 89.6699018716.

The spelling of 721008 in words is "seven hundred twenty-one thousand, eight".