6660123221 has 2 divisors, whose sum is σ = 6660123222. Its totient is φ = 6660123220.

The previous prime is 6660123199. The next prime is 6660123229. The reversal of 6660123221 is 1223210666.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 6644043121 + 16080100 = 81511^2 + 4010^2 .

It is a cyclic number.

It is not a de Polignac number, because 6660123221 - 2¹⁰ = 6660122197 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (6660123229) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 3330061610 + 3330061611.

It is an arithmetic number, because the mean of its divisors is an integer number (3330061611).

Almost surely, 2^6660123221 is an apocalyptic number.

It is an amenable number.

6660123221 is a deficient number, since it is larger than the sum of its proper divisors (1).

6660123221 is an equidigital number, since it uses as much as digits as its factorization.

6660123221 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 5184, while the sum is 29.

The square root of 6660123221 is about 81609.5779979286. The cubic root of 6660123221 is about 1881.4560943794.

Adding to 6660123221 its reverse (1223210666), we get a palindrome (7883333887).

The spelling of 6660123221 in words is "six billion, six hundred sixty million, one hundred twenty-three thousand, two hundred twenty-one".