63666 has 24 divisors (see below), whose sum is σ = 144144. Its totient is φ = 21060.

The previous prime is 63659. The next prime is 63667. The reversal of 63666 is 66636.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a nude number because it is divisible by every one of its digits.

It is not an unprimeable number, because it can be changed into a prime (63667) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 421 + ... + 551.

It is an arithmetic number, because the mean of its divisors is an integer number (6006).

2⁶³⁶⁶⁶ is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 63666, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (72072).

63666 is an abundant number, since it is smaller than the sum of its proper divisors (80478).

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

63666 is a wasteful number, since it uses less digits than its factorization.

With its predecessor (63665) it forms a Ruth-Aaron pair, since the sum of their distinct prime factors is the same (136).

63666 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 148 (or 136 counting only the distinct ones).

The product of its digits is 3888, while the sum is 27.

The square root of 63666 is about 252.3212238398. The cubic root of 63666 is about 39.9302952685.

It can be divided in two parts, 63 and 666, that added together give a 6-th power (729 = 3⁶).

The spelling of 63666 in words is "sixty-three thousand, six hundred sixty-six".