660639 has 16 divisors (see below), whose sum is σ = 1018112. Its totient is φ = 373248.

The previous prime is 660619. The next prime is 660643. The reversal of 660639 is 936066.

660639 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not a de Polignac number, because 660639 - 2⁵ = 660607 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (660619) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 3327 + ... + 3519.

It is an arithmetic number, because the mean of its divisors is an integer number (63632).

2⁶⁶⁰⁶³⁹ is an apocalyptic number.

660639 is a deficient number, since it is larger than the sum of its proper divisors (357473).

660639 is a wasteful number, since it uses less digits than its factorization.

660639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 366.

The product of its (nonzero) digits is 5832, while the sum is 30.

The square root of 660639 is about 812.7970226323. The cubic root of 660639 is about 87.0939663815.

The spelling of 660639 in words is "six hundred sixty thousand, six hundred thirty-nine".