660139 has 4 divisors (see below), whose sum is σ = 669256. Its totient is φ = 651024.

The previous prime is 660137. The next prime is 660157. The reversal of 660139 is 931066.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 660139 - 2¹ = 660137 is a prime.

It is a Duffinian number.

660139 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (660131) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 4449 + ... + 4594.

It is an arithmetic number, because the mean of its divisors is an integer number (167314).

2⁶⁶⁰¹³⁹ is an apocalyptic number.

660139 is a deficient number, since it is larger than the sum of its proper divisors (9117).

660139 is an equidigital number, since it uses as much as digits as its factorization.

660139 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9116.

The product of its (nonzero) digits is 972, while the sum is 25.

The square root of 660139 is about 812.4893845460. The cubic root of 660139 is about 87.0719886831.

The spelling of 660139 in words is "six hundred sixty thousand, one hundred thirty-nine".