2556216209 has 2 divisors, whose sum is σ = 2556216210. Its totient is φ = 2556216208.

The previous prime is 2556216191. The next prime is 2556216263. The reversal of 2556216209 is 9026126552.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 1588819600 + 967396609 = 39860^2 + 31103^2 .

It is a cyclic number.

It is not a de Polignac number, because 2556216209 - 2⁸ = 2556215953 is a prime.

It is not a weakly prime, because it can be changed into another prime (2556216269) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 1278108104 + 1278108105.

It is an arithmetic number, because the mean of its divisors is an integer number (1278108105).

Almost surely, 2^2556216209 is an apocalyptic number.

It is an amenable number.

2556216209 is a deficient number, since it is larger than the sum of its proper divisors (1).

2556216209 is an equidigital number, since it uses as much as digits as its factorization.

2556216209 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 64800, while the sum is 38.

The square root of 2556216209 is about 50559.0368678044. The cubic root of 2556216209 is about 1367.3064467207.

The spelling of 2556216209 in words is "two billion, five hundred fifty-six million, two hundred sixteen thousand, two hundred nine".