551206166221 has 2 divisors, whose sum is σ = 551206166222. Its totient is φ = 551206166220.

The previous prime is 551206166183. The next prime is 551206166233. The reversal of 551206166221 is 122661602155.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 441387496900 + 109818669321 = 664370^2 + 331389^2 .

It is a cyclic number.

It is not a de Polignac number, because 551206166221 - 2³¹ = 549058682573 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (551206166281) 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, 275603083110 + 275603083111.

It is an arithmetic number, because the mean of its divisors is an integer number (275603083111).

Almost surely, 2^551206166221 is an apocalyptic number.

It is an amenable number.

551206166221 is a deficient number, since it is larger than the sum of its proper divisors (1).

551206166221 is an equidigital number, since it uses as much as digits as its factorization.

551206166221 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 43200, while the sum is 37.

Adding to 551206166221 its reverse (122661602155), we get a palindrome (673867768376).

The spelling of 551206166221 in words is "five hundred fifty-one billion, two hundred six million, one hundred sixty-six thousand, two hundred twenty-one".