666138 has 16 divisors (see below), whose sum is σ = 1453536. Its totient is φ = 201840.

The previous prime is 666119. The next prime is 666139. The reversal of 666138 is 831666.

It is a Curzon number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 666138.

It is not an unprimeable number, because it can be changed into a prime (666139) by changing a digit.

666138 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4981 + ... + 5112.

It is an arithmetic number, because the mean of its divisors is an integer number (90846).

2⁶⁶⁶¹³⁸ is an apocalyptic number.

666138 is an abundant number, since it is smaller than the sum of its proper divisors (787398).

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

666138 is a wasteful number, since it uses less digits than its factorization.

666138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10109.

The product of its digits is 5184, while the sum is 30.

The square root of 666138 is about 816.1727758263. The cubic root of 666138 is about 87.3349487234.

The spelling of 666138 in words is "six hundred sixty-six thousand, one hundred thirty-eight".