66409757505 has 144 divisors (see below), whose sum is σ = 149952366720. Its totient is φ = 26548134912.

The previous prime is 66409757501. The next prime is 66409757521. The reversal of 66409757505 is 50575790466.

66409757505 is a `hidden beast` number, since 6 + 6 + 40 + 97 + 5 + 7 + 505 = 666.

It is not a de Polignac number, because 66409757505 - 2² = 66409757501 is a prime.

It is not an unprimeable number, because it can be changed into a prime (66409757501) by changing a digit.

It is a polite number, since it can be written in 143 ways as a sum of consecutive naturals, for example, 978637 + ... + 1044293.

It is an arithmetic number, because the mean of its divisors is an integer number (1041335880).

Almost surely, 2^66409757505 is an apocalyptic number.

66409757505 is a gapful number since it is divisible by the number (65) formed by its first and last digit.

It is an amenable number.

66409757505 is an abundant number, since it is smaller than the sum of its proper divisors (83542609215).

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

66409757505 is a wasteful number, since it uses less digits than its factorization.

66409757505 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 65720 (or 65704 counting only the distinct ones).

The product of its (nonzero) digits is 7938000, while the sum is 54.

The spelling of 66409757505 in words is "sixty-six billion, four hundred nine million, seven hundred fifty-seven thousand, five hundred five".