66331781131 has 20 divisors (see below), whose sum is σ = 84417277464. Its totient is φ = 51687081600.

The previous prime is 66331781129. The next prime is 66331781167. The reversal of 66331781131 is 13118713366.

It is not a de Polignac number, because 66331781131 - 2¹ = 66331781129 is a prime.

It is a super-2 number, since 2×66331781131² (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 (66331781101) 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 19 ways as a sum of consecutive naturals, for example, 1229350 + ... + 1282171.

Almost surely, 2^66331781131 is an apocalyptic number.

66331781131 is a deficient number, since it is larger than the sum of its proper divisors (18085496333).

66331781131 is an equidigital number, since it uses as much as digits as its factorization.

66331781131 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2511560 (or 2511539 counting only the distinct ones).

The product of its digits is 54432, while the sum is 40.

The spelling of 66331781131 in words is "sixty-six billion, three hundred thirty-one million, seven hundred eighty-one thousand, one hundred thirty-one".