666740 has 48 divisors (see below), whose sum is σ = 1551312. Its totient is φ = 239616.

The previous prime is 666737. The next prime is 666749. The reversal of 666740 is 47666.

It can be written as a sum of positive squares in 8 ways, for example, as 110224 + 556516 = 332^2 + 746^2 .

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (666749) 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, 12554 + ... + 12606.

It is an arithmetic number, because the mean of its divisors is an integer number (32319).

2⁶⁶⁶⁷⁴⁰ is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 666740, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (775656).

666740 is an abundant number, since it is smaller than the sum of its proper divisors (884572).

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

666740 is a wasteful number, since it uses less digits than its factorization.

666740 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 116 (or 114 counting only the distinct ones).

The product of its (nonzero) digits is 6048, while the sum is 29.

The square root of 666740 is about 816.5414870048. The cubic root of 666740 is about 87.3612494846.

The spelling of 666740 in words is "six hundred sixty-six thousand, seven hundred forty".