66681563 has 4 divisors (see below), whose sum is σ = 71810928. Its totient is φ = 61552200.

The previous prime is 66681547. The next prime is 66681607. The reversal of 66681563 is 36518666.

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 66681563 - 2⁴ = 66681547 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 66681563.

It is not an unprimeable number, because it can be changed into a prime (66681533) 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 3 ways as a sum of consecutive naturals, for example, 2564663 + ... + 2564688.

It is an arithmetic number, because the mean of its divisors is an integer number (17952732).

Almost surely, 2^66681563 is an apocalyptic number.

66681563 is a deficient number, since it is larger than the sum of its proper divisors (5129365).

66681563 is a wasteful number, since it uses less digits than its factorization.

66681563 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5129364.

The product of its digits is 155520, while the sum is 41.

The square root of 66681563 is about 8165.8779687184. The cubic root of 66681563 is about 405.5103316252.

The spelling of 66681563 in words is "sixty-six million, six hundred eighty-one thousand, five hundred sixty-three".