66521564 has 6 divisors (see below), whose sum is σ = 116412744. Its totient is φ = 33260780.

The previous prime is 66521551. The next prime is 66521573. The reversal of 66521564 is 46512566.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 8315192 + ... + 8315199.

It is an arithmetic number, because the mean of its divisors is an integer number (19402124).

Almost surely, 2^66521564 is an apocalyptic number.

It is an amenable number.

66521564 is a deficient number, since it is larger than the sum of its proper divisors (49891180).

66521564 is a wasteful number, since it uses less digits than its factorization.

66521564 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16630395 (or 16630393 counting only the distinct ones).

The product of its digits is 43200, while the sum is 35.

The square root of 66521564 is about 8156.0752816535. The cubic root of 66521564 is about 405.1857381044.

The spelling of 66521564 in words is "sixty-six million, five hundred twenty-one thousand, five hundred sixty-four".