155555909 has 2 divisors, whose sum is σ = 155555910. Its totient is φ = 155555908.

The previous prime is 155555903. The next prime is 155555921. The reversal of 155555909 is 909555551.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 83356900 + 72199009 = 9130^2 + 8497^2 .

It is a cyclic number.

It is not a de Polignac number, because 155555909 - 2²⁰ = 154507333 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 155555909.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (155555903) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 77777954 + 77777955.

It is an arithmetic number, because the mean of its divisors is an integer number (77777955).

Almost surely, 2^155555909 is an apocalyptic number.

It is an amenable number.

155555909 is a deficient number, since it is larger than the sum of its proper divisors (1).

155555909 is an equidigital number, since it uses as much as digits as its factorization.

155555909 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 253125, while the sum is 44.

The square root of 155555909 is about 12472.2054585386. The cubic root of 155555909 is about 537.8099560012.

The spelling of 155555909 in words is "one hundred fifty-five million, five hundred fifty-five thousand, nine hundred nine".