66559821 has 12 divisors (see below), whose sum is σ = 91705536. Its totient is φ = 42939960.

The previous prime is 66559813. The next prime is 66559837. The reversal of 66559821 is 12895566.

It is not a de Polignac number, because 66559821 - 2³ = 66559813 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66552821) by changing a digit.

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 11 ways as a sum of consecutive naturals, for example, 8661 + ... + 14426.

It is an arithmetic number, because the mean of its divisors is an integer number (7642128).

Almost surely, 2^66559821 is an apocalyptic number.

It is an amenable number.

66559821 is a deficient number, since it is larger than the sum of its proper divisors (25145715).

66559821 is a wasteful number, since it uses less digits than its factorization.

66559821 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23152 (or 23121 counting only the distinct ones).

The product of its digits is 129600, while the sum is 42.

The square root of 66559821 is about 8158.4202514948. The cubic root of 66559821 is about 405.2633982354.

The spelling of 66559821 in words is "sixty-six million, five hundred fifty-nine thousand, eight hundred twenty-one".