66115861864 has 64 divisors (see below), whose sum is σ = 134382402000. Its totient is φ = 30314532864.

The previous prime is 66115861849. The next prime is 66115861901. The reversal of 66115861864 is 46816851166.

It can be written as a sum of positive squares in 8 ways, for example, as 32020239364 + 34095622500 = 178942^2 + 184650^2 .

It is a Harshad number since it is a multiple of its sum of digits (52).

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 16326912 + ... + 16330960.

Almost surely, 2^66115861864 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66115861864, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (67191201000).

66115861864 is an abundant number, since it is smaller than the sum of its proper divisors (68266540136).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

66115861864 is a wasteful number, since it uses less digits than its factorization.

66115861864 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5062 (or 5058 counting only the distinct ones).

The product of its digits is 1658880, while the sum is 52.

The spelling of 66115861864 in words is "sixty-six billion, one hundred fifteen million, eight hundred sixty-one thousand, eight hundred sixty-four".