66005603 has 4 divisors (see below), whose sum is σ = 68134848. Its totient is φ = 63876360.

The previous prime is 66005591. The next prime is 66005609. The reversal of 66005603 is 30650066.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 66005603 - 2²⁰ = 64957027 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66005609) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1064576 + ... + 1064637.

It is an arithmetic number, because the mean of its divisors is an integer number (17033712).

Almost surely, 2^66005603 is an apocalyptic number.

66005603 is a deficient number, since it is larger than the sum of its proper divisors (2129245).

66005603 is a wasteful number, since it uses less digits than its factorization.

66005603 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2129244.

The product of its (nonzero) digits is 3240, while the sum is 26.

The square root of 66005603 is about 8124.3832381295. The cubic root of 66005603 is about 404.1354376315.

Adding to 66005603 its reverse (30650066), we get a palindrome (96655669).

The spelling of 66005603 in words is "sixty-six million, five thousand, six hundred three".