66515556544 has 56 divisors (see below), whose sum is σ = 135158163008. Its totient is φ = 32461067520.

The previous prime is 66515556521. The next prime is 66515556589. The reversal of 66515556544 is 44565551566.

66515556544 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a super-2 number, since 2×66515556544² (a number of 22 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 66515556491 and 66515556500.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4205419 + ... + 4221205.

Almost surely, 2^66515556544 is an apocalyptic number.

66515556544 is a gapful number since it is divisible by the number (64) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66515556544, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (67579081504).

66515556544 is an abundant number, since it is smaller than the sum of its proper divisors (68642606464).

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

66515556544 is a wasteful number, since it uses less digits than its factorization.

66515556544 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 17373 (or 17363 counting only the distinct ones).

The product of its digits is 10800000, while the sum is 52.

The spelling of 66515556544 in words is "sixty-six billion, five hundred fifteen million, five hundred fifty-six thousand, five hundred forty-four".