66408638520 has 128 divisors (see below), whose sum is σ = 228322022400. Its totient is φ = 15136766976.

The previous prime is 66408638509. The next prime is 66408638533. The reversal of 66408638520 is 2583680466.

66408638520 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a hoax number, since the sum of its digits (48) coincides with the sum of the digits of its distinct prime factors.

It is a self number, because there is not a number n which added to its sum of digits gives 66408638520.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 191452 + ... + 411668.

It is an arithmetic number, because the mean of its divisors is an integer number (1783765800).

Almost surely, 2^66408638520 is an apocalyptic number.

66408638520 is a gapful number since it is divisible by the number (60) 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 66408638520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (114161011200).

66408638520 is an abundant number, since it is smaller than the sum of its proper divisors (161913383880).

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

66408638520 is a wasteful number, since it uses less digits than its factorization.

66408638520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 220597 (or 220593 counting only the distinct ones).

The product of its (nonzero) digits is 1658880, while the sum is 48.

The spelling of 66408638520 in words is "sixty-six billion, four hundred eight million, six hundred thirty-eight thousand, five hundred twenty".