55212809 has 2 divisors, whose sum is σ = 55212810. Its totient is φ = 55212808.

The previous prime is 55212797. The next prime is 55212823. The reversal of 55212809 is 90821255.

55212809 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 38402809 + 16810000 = 6197^2 + 4100^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-55212809 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (55212709) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27606404 + 27606405.

It is an arithmetic number, because the mean of its divisors is an integer number (27606405).

Almost surely, 2^55212809 is an apocalyptic number.

It is an amenable number.

55212809 is a deficient number, since it is larger than the sum of its proper divisors (1).

55212809 is an equidigital number, since it uses as much as digits as its factorization.

55212809 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 7200, while the sum is 32.

The square root of 55212809 is about 7430.5322151243. The cubic root of 55212809 is about 380.7851011968.

The spelling of 55212809 in words is "fifty-five million, two hundred twelve thousand, eight hundred nine".