121556221 has 2 divisors, whose sum is σ = 121556222. Its totient is φ = 121556220.

The previous prime is 121556213. The next prime is 121556249. The reversal of 121556221 is 122655121.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 118265625 + 3290596 = 10875^2 + 1814^2 .

It is an emirp because it is prime and its reverse (122655121) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 121556221 - 2³ = 121556213 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (121556321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 60778110 + 60778111.

It is an arithmetic number, because the mean of its divisors is an integer number (60778111).

Almost surely, 2^121556221 is an apocalyptic number.

It is an amenable number.

121556221 is a deficient number, since it is larger than the sum of its proper divisors (1).

121556221 is an equidigital number, since it uses as much as digits as its factorization.

121556221 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 1200, while the sum is 25.

The square root of 121556221 is about 11025.2537839272. The cubic root of 121556221 is about 495.3654696495.

The spelling of 121556221 in words is "one hundred twenty-one million, five hundred fifty-six thousand, two hundred twenty-one".