66811563 has 72 divisors (see below), whose sum is σ = 124281248. Its totient is φ = 33675264.

The previous prime is 66811517. The next prime is 66811567. The reversal of 66811563 is 36511866.

It is a happy number.

It is not a de Polignac number, because 66811563 - 2⁹ = 66811051 is a prime.

It is not an unprimeable number, because it can be changed into a prime (66811567) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 71 ways as a sum of consecutive naturals, for example, 688731 + ... + 688827.

Almost surely, 2^66811563 is an apocalyptic number.

66811563 is a gapful number since it is divisible by the number (63) formed by its first and last digit.

66811563 is a deficient number, since it is larger than the sum of its proper divisors (57469685).

66811563 is a wasteful number, since it uses less digits than its factorization.

66811563 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 181 (or 149 counting only the distinct ones).

The product of its digits is 25920, while the sum is 36.

The square root of 66811563 is about 8173.8340452936. The cubic root of 66811563 is about 405.7736833916.

The spelling of 66811563 in words is "sixty-six million, eight hundred eleven thousand, five hundred sixty-three".