66887221 has 4 divisors (see below), whose sum is σ = 66959244. Its totient is φ = 66815200.

The previous prime is 66887209. The next prime is 66887267. The reversal of 66887221 is 12278866.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 48302500 + 18584721 = 6950^2 + 4311^2 .

It is a cyclic number.

It is not a de Polignac number, because 66887221 - 2⁵ = 66887189 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66887281) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 34600 + ... + 36481.

It is an arithmetic number, because the mean of its divisors is an integer number (16739811).

Almost surely, 2^66887221 is an apocalyptic number.

It is an amenable number.

66887221 is a deficient number, since it is larger than the sum of its proper divisors (72023).

66887221 is an equidigital number, since it uses as much as digits as its factorization.

66887221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 72022.

The product of its digits is 64512, while the sum is 40.

The square root of 66887221 is about 8178.4607965069. The cubic root of 66887221 is about 405.9267928381.

The spelling of 66887221 in words is "sixty-six million, eight hundred eighty-seven thousand, two hundred twenty-one".