660636221 has 16 divisors (see below), whose sum is σ = 776688384. Its totient is φ = 550053504.

The previous prime is 660636217. The next prime is 660636271. The reversal of 660636221 is 122636066.

It is not a de Polignac number, because 660636221 - 2² = 660636217 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 (660636271) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 190721 + ... + 194153.

It is an arithmetic number, because the mean of its divisors is an integer number (48543024).

Almost surely, 2^660636221 is an apocalyptic number.

It is an amenable number.

660636221 is a deficient number, since it is larger than the sum of its proper divisors (116052163).

660636221 is a wasteful number, since it uses less digits than its factorization.

660636221 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4220.

The product of its (nonzero) digits is 15552, while the sum is 32.

The square root of 660636221 is about 25702.8446091089. The cubic root of 660636221 is about 870.9384426005.

The spelling of 660636221 in words is "six hundred sixty million, six hundred thirty-six thousand, two hundred twenty-one".