66878614881 has 81 divisors (see below), whose sum is σ = 110717544249. Its totient is φ = 38878242624.

The previous prime is 66878614871. The next prime is 66878614903. The reversal of 66878614881 is 18841687866.

The square root of 66878614881 is 258609.

It is a perfect power (a square), and thus also a powerful number.

66878614881 is a `hidden beast` number, since 6 + 6 + 8 + 7 + 8 + 614 + 8 + 8 + 1 = 666.

66878614881 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 4 ways, for example, as 1436789025 + 65441825856 = 37905^2 + 255816^2 .

It is not a de Polignac number, because 66878614881 - 2²⁵ = 66845060449 is a prime.

It is a super-2 number, since 2×66878614881² (a number of 22 digits) contains 22 as substring.

Its product of digits (24772608) is a multiple of the sum of its prime divisors (384).

It is not an unprimeable number, because it can be changed into a prime (66878614811) by changing a digit.

It is a polite number, since it can be written in 80 ways as a sum of consecutive naturals, for example, 191629095 + ... + 191629443.

Almost surely, 2^66878614881 is an apocalyptic number.

66878614881 is the 258609-th square number.

66878614881 is the 129305-th centered octagonal number.

It is an amenable number.

66878614881 is a deficient number, since it is larger than the sum of its proper divisors (43838929368).

66878614881 is a wasteful number, since it uses less digits than its factorization.

66878614881 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 768 (or 384 counting only the distinct ones).

The product of its digits is 24772608, while the sum is 63.

The spelling of 66878614881 in words is "sixty-six billion, eight hundred seventy-eight million, six hundred fourteen thousand, eight hundred eighty-one".