66518701600 has 144 divisors (see below), whose sum is σ = 185167789128. Its totient is φ = 23115939840.

The previous prime is 66518701559. The next prime is 66518701699. The reversal of 66518701600 is 610781566.

It can be written as a sum of positive squares in 12 ways, for example, as 15726163216 + 50792538384 = 125404^2 + 225372^2 .

It is a Harshad number since it is a multiple of its sum of digits (40).

It is an unprimeable number.

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 23 ways as a sum of consecutive naturals, for example, 11319 + ... + 364918.

Almost surely, 2^66518701600 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 66518701600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (92583894564).

66518701600 is an abundant number, since it is smaller than the sum of its proper divisors (118649087528).

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

66518701600 is a wasteful number, since it uses less digits than its factorization.

66518701600 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 376287 (or 376274 counting only the distinct ones).

The product of its (nonzero) digits is 60480, while the sum is 40.

The spelling of 66518701600 in words is "sixty-six billion, five hundred eighteen million, seven hundred one thousand, six hundred".