66518138736 has 320 divisors, whose sum is σ = 221745807360. Its totient is φ = 18699621120.

The previous prime is 66518138723. The next prime is 66518138761. The reversal of 66518138736 is 63783181566.

66518138736 is a `hidden beast` number, since 6 + 6 + 518 + 13 + 87 + 36 = 666.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 54035241 + ... + 54036471.

It is an arithmetic number, because the mean of its divisors is an integer number (692955648).

Almost surely, 2^66518138736 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 66518138736, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (110872903680).

66518138736 is an abundant number, since it is smaller than the sum of its proper divisors (155227668624).

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

66518138736 is a wasteful number, since it uses less digits than its factorization.

66518138736 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1529 (or 1517 counting only the distinct ones).

The product of its digits is 4354560, while the sum is 54.

The spelling of 66518138736 in words is "sixty-six billion, five hundred eighteen million, one hundred thirty-eight thousand, seven hundred thirty-six".