66561517736 has 32 divisors (see below), whose sum is σ = 148833210240. Its totient is φ = 27286087488.

The previous prime is 66561517733. The next prime is 66561517741. The reversal of 66561517736 is 63771516566.

66561517736 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is not an unprimeable number, because it can be changed into a prime (66561517733) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 25837811 + ... + 25840386.

It is an arithmetic number, because the mean of its divisors is an integer number (4651037820).

Almost surely, 2^66561517736 is an apocalyptic number.

It is an amenable number.

66561517736 is an abundant number, since it is smaller than the sum of its proper divisors (82271692504).

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

66561517736 is a wasteful number, since it uses less digits than its factorization.

66561517736 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 51678233 (or 51678229 counting only the distinct ones).

The product of its digits is 4762800, while the sum is 53.

The spelling of 66561517736 in words is "sixty-six billion, five hundred sixty-one million, five hundred seventeen thousand, seven hundred thirty-six".