55545221 has 2 divisors, whose sum is σ = 55545222. Its totient is φ = 55545220.

The previous prime is 55545209. The next prime is 55545223. The reversal of 55545221 is 12254555.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 48580900 + 6964321 = 6970^2 + 2639^2 .

It is a cyclic number.

It is not a de Polignac number, because 55545221 - 2⁶ = 55545157 is a prime.

Together with 55545223, it forms a pair of twin primes.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (55545223) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27772610 + 27772611.

It is an arithmetic number, because the mean of its divisors is an integer number (27772611).

Almost surely, 2^55545221 is an apocalyptic number.

It is an amenable number.

55545221 is a deficient number, since it is larger than the sum of its proper divisors (1).

55545221 is an equidigital number, since it uses as much as digits as its factorization.

55545221 is an evil number, because the sum of its binary digits is even.

The product of its digits is 10000, while the sum is 29.

The square root of 55545221 is about 7452.8666296936. The cubic root of 55545221 is about 381.5477524913.

Adding to 55545221 its reverse (12254555), we get a palindrome (67799776).

The spelling of 55545221 in words is "fifty-five million, five hundred forty-five thousand, two hundred twenty-one".