66540511504566 has 128 divisors (see below), whose sum is σ = 163625011200000. Its totient is φ = 19875308787360.

The previous prime is 66540511504477. The next prime is 66540511504661.

66540511504566 is a `hidden beast` number, since 6 + 6 + 540 + 5 + 1 + 1 + 50 + 45 + 6 + 6 = 666.

66540511504566 is nontrivially palindromic in base 10.

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

It is a Curzon number.

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, 26925045 + ... + 29292303.

It is an arithmetic number, because the mean of its divisors is an integer number (1278320400000).

Almost surely, 2^{66540511504566} is an apocalyptic number.

66540511504566 is a gapful number since it is divisible by the number (66) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 66540511504566, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (81812505600000).

66540511504566 is an abundant number, since it is smaller than the sum of its proper divisors (97084499695434).

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

66540511504566 is a wasteful number, since it uses less digits than its factorization.

66540511504566 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2367959 (or 2367953 counting only the distinct ones).

The product of its (nonzero) digits is 12960000, while the sum is 54.

The spelling of 66540511504566 in words is "sixty-six trillion, five hundred forty billion, five hundred eleven million, five hundred four thousand, five hundred sixty-six".