221212129 has 2 divisors, whose sum is σ = 221212130. Its totient is φ = 221212128.

The previous prime is 221212111. The next prime is 221212133. The reversal of 221212129 is 921212122.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 152769600 + 68442529 = 12360^2 + 8273^2 .

It is a cyclic number.

It is not a de Polignac number, because 221212129 - 2²¹ = 219114977 is a prime.

It is not a weakly prime, because it can be changed into another prime (221212729) 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 as a sum of consecutive naturals, namely, 110606064 + 110606065.

It is an arithmetic number, because the mean of its divisors is an integer number (110606065).

Almost surely, 2^221212129 is an apocalyptic number.

It is an amenable number.

221212129 is a deficient number, since it is larger than the sum of its proper divisors (1).

221212129 is an equidigital number, since it uses as much as digits as its factorization.

221212129 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 288, while the sum is 22.

The square root of 221212129 is about 14873.2017064249. The cubic root of 221212129 is about 604.7877396678.

It can be divided in two parts, 2212 and 12129, that added together give a palindrome (14341).

The spelling of 221212129 in words is "two hundred twenty-one million, two hundred twelve thousand, one hundred twenty-nine".