66115861591 has 24 divisors (see below), whose sum is σ = 75890957184. Its totient is φ = 57245054400.

The previous prime is 66115861529. The next prime is 66115861681. The reversal of 66115861591 is 19516851166.

It is not a de Polignac number, because 66115861591 - 2⁷ = 66115861463 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66115891591) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 404250 + ... + 543736.

It is an arithmetic number, because the mean of its divisors is an integer number (3162123216).

Almost surely, 2^66115861591 is an apocalyptic number.

66115861591 is a deficient number, since it is larger than the sum of its proper divisors (9775095593).

66115861591 is a wasteful number, since it uses less digits than its factorization.

66115861591 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 139639 (or 139620 counting only the distinct ones).

The product of its digits is 388800, while the sum is 49.

The spelling of 66115861591 in words is "sixty-six billion, one hundred fifteen million, eight hundred sixty-one thousand, five hundred ninety-one".