667638 has 24 divisors (see below), whose sum is σ = 1497600. Its totient is φ = 214704.

The previous prime is 667631. The next prime is 667643. The reversal of 667638 is 836766.

It is a happy number.

It is an Ulam number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (667631) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 118 + ... + 1161.

It is an arithmetic number, because the mean of its divisors is an integer number (62400).

2⁶⁶⁷⁶³⁸ is an apocalyptic number.

667638 is an abundant number, since it is smaller than the sum of its proper divisors (829962).

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

667638 is a wasteful number, since it uses less digits than its factorization.

667638 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1316 (or 1313 counting only the distinct ones).

The product of its digits is 36288, while the sum is 36.

The square root of 667638 is about 817.0911821823. The cubic root of 667638 is about 87.4004527762.

The spelling of 667638 in words is "six hundred sixty-seven thousand, six hundred thirty-eight".