66716884681 has 4 divisors (see below), whose sum is σ = 67810604164. Its totient is φ = 65623165200.

The previous prime is 66716884657. The next prime is 66716884711. The reversal of 66716884681 is 18648861766.

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

It can be written as a sum of positive squares in 2 ways, for example, as 18430777600 + 48286107081 = 135760^2 + 219741^2 .

It is a cyclic number.

It is not a de Polignac number, because 66716884681 - 2¹⁵ = 66716851913 is a prime.

It is a super-2 number, since 2×66716884681² (a number of 22 digits) contains 22 as substring.

It is a Harshad number since it is a multiple of its sum of digits (61), and also a Moran number because the ratio is a prime number: 1093719421 = 66716884681 / (6 + 6 + 7 + 1 + 6 + 8 + 8 + 4 + 6 + 8 + 1).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66716884631) 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, 546859650 + ... + 546859771.

It is an arithmetic number, because the mean of its divisors is an integer number (16952651041).

Almost surely, 2^66716884681 is an apocalyptic number.

66716884681 is a gapful number since it is divisible by the number (61) formed by its first and last digit.

It is an amenable number.

66716884681 is a deficient number, since it is larger than the sum of its proper divisors (1093719483).

66716884681 is a wasteful number, since it uses less digits than its factorization.

66716884681 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1093719482.

The product of its digits is 18579456, while the sum is 61.

The spelling of 66716884681 in words is "sixty-six billion, seven hundred sixteen million, eight hundred eighty-four thousand, six hundred eighty-one".