66638 has 16 divisors (see below), whose sum is σ = 117936. Its totient is φ = 27840.

The previous prime is 66629. The next prime is 66643. The reversal of 66638 is 83666.

66638 = 7² + 8² + ... + 58².

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 66638.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 66638.

It is an unprimeable number.

66638 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, 170 + ... + 402.

It is an arithmetic number, because the mean of its divisors is an integer number (7371).

2⁶⁶⁶³⁸ is an apocalyptic number.

66638 is a deficient number, since it is larger than the sum of its proper divisors (51298).

66638 is a wasteful number, since it uses less digits than its factorization.

66638 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 259.

The product of its digits is 5184, while the sum is 29.

The square root of 66638 is about 258.1433710170. The cubic root of 66638 is about 40.5422005887.

The spelling of 66638 in words is "sixty-six thousand, six hundred thirty-eight".