66147221 has 16 divisors (see below), whose sum is σ = 81181440. Its totient is φ = 52604160.

The previous prime is 66147217. The next prime is 66147239. The reversal of 66147221 is 12274166.

It is not a de Polignac number, because 66147221 - 2² = 66147217 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (66147251) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4535 + ... + 12363.

It is an arithmetic number, because the mean of its divisors is an integer number (5073840).

Almost surely, 2^66147221 is an apocalyptic number.

It is an amenable number.

66147221 is a deficient number, since it is larger than the sum of its proper divisors (15034219).

66147221 is a wasteful number, since it uses less digits than its factorization.

66147221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7924.

The product of its digits is 4032, while the sum is 29.

The square root of 66147221 is about 8133.0941836425. The cubic root of 66147221 is about 404.4242614416.

The spelling of 66147221 in words is "sixty-six million, one hundred forty-seven thousand, two hundred twenty-one".