66581664 has 48 divisors (see below), whose sum is σ = 175317408. Its totient is φ = 22125312.

The previous prime is 66581653. The next prime is 66581689. The reversal of 66581664 is 46618566.

It is a tau number, because it is divible by the number of its divisors (48).

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 37239 + ... + 38985.

It is an arithmetic number, because the mean of its divisors is an integer number (3652446).

Almost surely, 2^66581664 is an apocalyptic number.

It is an amenable number.

66581664 is an abundant number, since it is smaller than the sum of its proper divisors (108735744).

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

66581664 is a wasteful number, since it uses less digits than its factorization.

66581664 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2157 (or 2149 counting only the distinct ones).

The product of its digits is 207360, while the sum is 42.

The square root of 66581664 is about 8159.7588199652. The cubic root of 66581664 is about 405.3077252789.

The spelling of 66581664 in words is "sixty-six million, five hundred eighty-one thousand, six hundred sixty-four".