55218109 has 2 divisors, whose sum is σ = 55218110. Its totient is φ = 55218108.

The previous prime is 55218073. The next prime is 55218113. The reversal of 55218109 is 90181255.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 54434884 + 783225 = 7378^2 + 885^2 .

It is a cyclic number.

It is not a de Polignac number, because 55218109 - 2⁹ = 55217597 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (55218169) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 27609054 + 27609055.

It is an arithmetic number, because the mean of its divisors is an integer number (27609055).

Almost surely, 2^55218109 is an apocalyptic number.

It is an amenable number.

55218109 is a deficient number, since it is larger than the sum of its proper divisors (1).

55218109 is an equidigital number, since it uses as much as digits as its factorization.

55218109 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3600, while the sum is 31.

The square root of 55218109 is about 7430.8888432004. Note that the first 4 decimals coincide. The cubic root of 55218109 is about 380.7972849424.

The spelling of 55218109 in words is "fifty-five million, two hundred eighteen thousand, one hundred nine".