66185138881 has 8 divisors (see below), whose sum is σ = 66819622760. Its totient is φ = 65551151232.

The previous prime is 66185138863. The next prime is 66185138893. The reversal of 66185138881 is 18883158166.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 18099666225 + 48085472656 = 134535^2 + 219284^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 66185138881 - 2¹⁷ = 66185007809 is a prime.

It is a super-2 number, since 2×66185138881² (a number of 22 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (66185178881) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 146791 + ... + 392323.

It is an arithmetic number, because the mean of its divisors is an integer number (8352452845).

Almost surely, 2^66185138881 is an apocalyptic number.

It is an amenable number.

66185138881 is a deficient number, since it is larger than the sum of its proper divisors (634483879).

66185138881 is a wasteful number, since it uses less digits than its factorization.

66185138881 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 248115.

The product of its digits is 2211840, while the sum is 55.

The spelling of 66185138881 in words is "sixty-six billion, one hundred eighty-five million, one hundred thirty-eight thousand, eight hundred eighty-one".