8218220509 has 2 divisors, whose sum is σ = 8218220510. Its totient is φ = 8218220508.

The previous prime is 8218220503. The next prime is 8218220533. The reversal of 8218220509 is 9050228128.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 8043399225 + 174821284 = 89685^2 + 13222^2 .

It is a cyclic number.

It is not a de Polignac number, because 8218220509 - 2²³ = 8209831901 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (8218220503) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 4109110254 + 4109110255.

It is an arithmetic number, because the mean of its divisors is an integer number (4109110255).

Almost surely, 2^8218220509 is an apocalyptic number.

It is an amenable number.

8218220509 is a deficient number, since it is larger than the sum of its proper divisors (1).

8218220509 is an equidigital number, since it uses as much as digits as its factorization.

8218220509 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 23040, while the sum is 37.

The square root of 8218220509 is about 90654.4014871865. The cubic root of 8218220509 is about 2018.0221555741.

The spelling of 8218220509 in words is "eight billion, two hundred eighteen million, two hundred twenty thousand, five hundred nine".