66878709181 has 4 divisors (see below), whose sum is σ = 67725275200. Its totient is φ = 66032143164.

The previous prime is 66878709169. The next prime is 66878709193. The reversal of 66878709181 is 18190787866.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 18190787866 = 2 ⋅9095393933.

It is an interprime number because it is at equal distance from previous prime (66878709169) and next prime (66878709193).

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66878709181 is a prime.

It is a super-2 number, since 2×66878709181² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66878703181) 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, 423282891 + ... + 423283048.

It is an arithmetic number, because the mean of its divisors is an integer number (16931318800).

Almost surely, 2^66878709181 is an apocalyptic number.

It is an amenable number.

66878709181 is a deficient number, since it is larger than the sum of its proper divisors (846566019).

66878709181 is an equidigital number, since it uses as much as digits as its factorization.

66878709181 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 846566018.

The product of its (nonzero) digits is 8128512, while the sum is 61.

The spelling of 66878709181 in words is "sixty-six billion, eight hundred seventy-eight million, seven hundred nine thousand, one hundred eighty-one".