66116661631 has 4 divisors (see below), whose sum is σ = 66117574600. Its totient is φ = 66115748664.

The previous prime is 66116661617. The next prime is 66116661641. The reversal of 66116661631 is 13616661166.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 13616661166 = 2 ⋅6808330583.

It is a cyclic number.

It is not a de Polignac number, because 66116661631 - 2⁷ = 66116661503 is a prime.

It is a super-2 number, since 2×66116661631² (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 (66116661641) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 337521 + ... + 496138.

It is an arithmetic number, because the mean of its divisors is an integer number (16529393650).

Almost surely, 2^66116661631 is an apocalyptic number.

66116661631 is a deficient number, since it is larger than the sum of its proper divisors (912969).

66116661631 is an equidigital number, since it uses as much as digits as its factorization.

66116661631 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 912968.

The product of its digits is 139968, while the sum is 43.

The spelling of 66116661631 in words is "sixty-six billion, one hundred sixteen million, six hundred sixty-one thousand, six hundred thirty-one".