66549204771840 has 2640 divisors, whose sum is σ = 284412684905712. Its totient is φ = 14832648585216.

The previous prime is 66549204771779. The next prime is 66549204771851. The reversal of 66549204771840 is 4817740294566.

66549204771840 is a `hidden beast` number, since 6 + 6 + 549 + 2 + 0 + 4 + 7 + 7 + 1 + 84 + 0 = 666.

It can be written as a sum of positive squares in 8 ways, for example, as 4953580240896 + 61595624530944 = 2225664^2 + 7848288^2 .

It is a Harshad number since it is a multiple of its sum of digits (63).

It is an unprimeable number.

It is a polite number, since it can be written in 239 ways as a sum of consecutive naturals, for example, 167630238522 + ... + 167630238918.

Almost surely, 2^{66549204771840} is an apocalyptic number.

66549204771840 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 66549204771840, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (142206342452856).

66549204771840 is an abundant number, since it is smaller than the sum of its proper divisors (217863480133872).

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

66549204771840 is a wasteful number, since it uses less digits than its factorization.

66549204771840 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 634 (or 600 counting only the distinct ones).

The product of its (nonzero) digits is 81285120, while the sum is 63.

The spelling of 66549204771840 in words is "sixty-six trillion, five hundred forty-nine billion, two hundred four million, seven hundred seventy-one thousand, eight hundred forty".