66151821680 has 80 divisors (see below), whose sum is σ = 183417260544. Its totient is φ = 21694506240.

The previous prime is 66151821679. The next prime is 66151821689. The reversal of 66151821680 is 8612815166.

It is a tau number, because it is divible by the number of its divisors (80).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66151821689) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2555126 + ... + 2580885.

Almost surely, 2^66151821680 is an apocalyptic number.

It is an amenable number.

66151821680 is an abundant number, since it is smaller than the sum of its proper divisors (117265438864).

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

66151821680 is a wasteful number, since it uses less digits than its factorization.

66151821680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5136054 (or 5136048 counting only the distinct ones).

The product of its (nonzero) digits is 138240, while the sum is 44.

The spelling of 66151821680 in words is "sixty-six billion, one hundred fifty-one million, eight hundred twenty-one thousand, six hundred eighty".