660999 has 4 divisors (see below), whose sum is σ = 881336. Its totient is φ = 440664.

The previous prime is 660983. The next prime is 661009. The reversal of 660999 is 999066.

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

It is not a de Polignac number, because 660999 - 2⁴ = 660983 is a prime.

It is a D-number.

It is a Duffinian number.

660999 is a modest number, since divided by 999 gives 660 as remainder.

660999 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (660949) 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, 110164 + ... + 110169.

It is an arithmetic number, because the mean of its divisors is an integer number (220334).

2⁶⁶⁰⁹⁹⁹ is an apocalyptic number.

660999 is a deficient number, since it is larger than the sum of its proper divisors (220337).

660999 is a wasteful number, since it uses less digits than its factorization.

660999 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 220336.

The product of its (nonzero) digits is 26244, while the sum is 39.

The square root of 660999 is about 813.0184499752. The cubic root of 660999 is about 87.1097834588.

The spelling of 660999 in words is "six hundred sixty thousand, nine hundred ninety-nine".