66213344640 has 64 divisors (see below), whose sum is σ = 211055042160. Its totient is φ = 17656891392.

The previous prime is 66213344627. The next prime is 66213344641. The reversal of 66213344640 is 4644331266.

It is a tau number, because it is divible by the number of its divisors (64).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66213344641) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 17241139 + ... + 17244978.

Almost surely, 2^66213344640 is an apocalyptic number.

66213344640 is a gapful number since it is divisible by the number (60) formed by its first and last digit.

It is an amenable number.

66213344640 is an abundant number, since it is smaller than the sum of its proper divisors (144841697520).

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

66213344640 is a wasteful number, since it uses less digits than its factorization.

66213344640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 34486139 (or 34486127 counting only the distinct ones).

The product of its (nonzero) digits is 248832, while the sum is 39.

The spelling of 66213344640 in words is "sixty-six billion, two hundred thirteen million, three hundred forty-four thousand, six hundred forty".