66542155646400 has 840 divisors, whose sum is σ = 280788341729280. Its totient is φ = 15141384898560.

The previous prime is 66542155646399. The next prime is 66542155646401. The reversal of 66542155646400 is 464655124566.

66542155646400 is a `hidden beast` number, since 6 + 6 + 5 + 4 + 2 + 1 + 556 + 46 + 40 + 0 = 666.

It is an interprime number because it is at equal distance from previous prime (66542155646399) and next prime (66542155646401).

It is a tau number, because it is divible by the number of its divisors (840).

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

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66542155646401) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 119 ways as a sum of consecutive naturals, for example, 202141141 + ... + 202470059.

It is an arithmetic number, because the mean of its divisors is an integer number (334271835392).

Almost surely, 2^{66542155646400} is an apocalyptic number.

66542155646400 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 66542155646400, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (140394170864640).

66542155646400 is an abundant number, since it is smaller than the sum of its proper divisors (214246186082880).

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

66542155646400 is a wasteful number, since it uses less digits than its factorization.

66542155646400 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 329183 (or 329159 counting only the distinct ones).

The product of its (nonzero) digits is 20736000, while the sum is 54.

The spelling of 66542155646400 in words is "sixty-six trillion, five hundred forty-two billion, one hundred fifty-five million, six hundred forty-six thousand, four hundred".