66643605 has 48 divisors (see below), whose sum is σ = 133660800. Its totient is φ = 30086784.

The previous prime is 66643601. The next prime is 66643607. The reversal of 66643605 is 50634666.

It is not a de Polignac number, because 66643605 - 2² = 66643601 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 66643605.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66643601) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 24871 + ... + 27419.

It is an arithmetic number, because the mean of its divisors is an integer number (2784600).

Almost surely, 2^66643605 is an apocalyptic number.

It is an amenable number.

66643605 is an abundant number, since it is smaller than the sum of its proper divisors (67017195).

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

66643605 is a wasteful number, since it uses less digits than its factorization.

66643605 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2650 (or 2647 counting only the distinct ones).

The product of its (nonzero) digits is 77760, while the sum is 36.

The square root of 66643605 is about 8163.5534542257. The cubic root of 66643605 is about 405.4333724076.

The spelling of 66643605 in words is "sixty-six million, six hundred forty-three thousand, six hundred five".