66549221 has 4 divisors (see below), whose sum is σ = 66847872. Its totient is φ = 66250572.

The previous prime is 66549163. The next prime is 66549239. The reversal of 66549221 is 12294566.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-66549221 is a prime.

It is a super-3 number, since 3×66549221³ (a number of 24 digits) contains 333 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66543221) 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 3 ways as a sum of consecutive naturals, for example, 148991 + ... + 149436.

It is an arithmetic number, because the mean of its divisors is an integer number (16711968).

Almost surely, 2^66549221 is an apocalyptic number.

It is an amenable number.

66549221 is a deficient number, since it is larger than the sum of its proper divisors (298651).

66549221 is a wasteful number, since it uses less digits than its factorization.

66549221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 298650.

The product of its digits is 25920, while the sum is 35.

The square root of 66549221 is about 8157.7705900571. The cubic root of 66549221 is about 405.2418836539.

The spelling of 66549221 in words is "sixty-six million, five hundred forty-nine thousand, two hundred twenty-one".