555551221 has 2 divisors, whose sum is σ = 555551222. Its totient is φ = 555551220.

The previous prime is 555551201. The next prime is 555551273. The reversal of 555551221 is 122155555.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 411887025 + 143664196 = 20295^2 + 11986^2 .

It is a cyclic number.

It is not a de Polignac number, because 555551221 - 2¹¹ = 555549173 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (555551201) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 277775610 + 277775611.

It is an arithmetic number, because the mean of its divisors is an integer number (277775611).

Almost surely, 2^555551221 is an apocalyptic number.

It is an amenable number.

555551221 is a deficient number, since it is larger than the sum of its proper divisors (1).

555551221 is an equidigital number, since it uses as much as digits as its factorization.

555551221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 12500, while the sum is 31.

The square root of 555551221 is about 23570.1340895634. The cubic root of 555551221 is about 822.0685534513.

The spelling of 555551221 in words is "five hundred fifty-five million, five hundred fifty-one thousand, two hundred twenty-one".