720644 has 6 divisors (see below), whose sum is σ = 1261134. Its totient is φ = 360320.

The previous prime is 720619. The next prime is 720653. The reversal of 720644 is 446027.

It can be written as a sum of positive squares in only one way, i.e., 407044 + 313600 = 638^2 + 560^2 .

It is an unprimeable number.

720644 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 (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 90077 + ... + 90084.

It is an arithmetic number, because the mean of its divisors is an integer number (210189).

2⁷²⁰⁶⁴⁴ is an apocalyptic number.

It is an amenable number.

720644 is a deficient number, since it is larger than the sum of its proper divisors (540490).

720644 is a wasteful number, since it uses less digits than its factorization.

720644 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 180165 (or 180163 counting only the distinct ones).

The product of its (nonzero) digits is 1344, while the sum is 23.

The square root of 720644 is about 848.9075332449. The cubic root of 720644 is about 89.6548094184.

The spelling of 720644 in words is "seven hundred twenty thousand, six hundred forty-four".