2155123309 has 2 divisors, whose sum is σ = 2155123310. Its totient is φ = 2155123308.

The previous prime is 2155123261. The next prime is 2155123331. The reversal of 2155123309 is 9033215512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 1393528900 + 761594409 = 37330^2 + 27597^2 .

It is a cyclic number.

It is not a de Polignac number, because 2155123309 - 2¹⁷ = 2154992237 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (2155123339) 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, 1077561654 + 1077561655.

It is an arithmetic number, because the mean of its divisors is an integer number (1077561655).

Almost surely, 2^2155123309 is an apocalyptic number.

It is an amenable number.

2155123309 is a deficient number, since it is larger than the sum of its proper divisors (1).

2155123309 is an equidigital number, since it uses as much as digits as its factorization.

2155123309 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8100, while the sum is 31.

The square root of 2155123309 is about 46423.3056664430. The cubic root of 2155123309 is about 1291.6872557652.

The spelling of 2155123309 in words is "two billion, one hundred fifty-five million, one hundred twenty-three thousand, three hundred nine".