721608 has 32 divisors (see below), whose sum is σ = 1827360. Its totient is φ = 237440.

The previous prime is 721597. The next prime is 721613. The reversal of 721608 is 806127.

It is a hoax number, since the sum of its digits (24) coincides with the sum of the digits of its distinct prime factors.

It is a Harshad number since it is a multiple of its sum of digits (24).

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 721608.

It is an unprimeable 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 7 ways as a sum of consecutive naturals, for example, 2428 + ... + 2708.

It is an arithmetic number, because the mean of its divisors is an integer number (57105).

2⁷²¹⁶⁰⁸ is an apocalyptic number.

It is an amenable number.

721608 is an abundant number, since it is smaller than the sum of its proper divisors (1105752).

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

721608 is a wasteful number, since it uses less digits than its factorization.

721608 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 397 (or 393 counting only the distinct ones).

The product of its (nonzero) digits is 672, while the sum is 24.

The square root of 721608 is about 849.4751320669. The cubic root of 721608 is about 89.6947684584.

The spelling of 721608 in words is "seven hundred twenty-one thousand, six hundred eight".