155509 has 2 divisors, whose sum is σ = 155510. Its totient is φ = 155508.

The previous prime is 155501. The next prime is 155521. The reversal of 155509 is 905551.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 140625 + 14884 = 375^2 + 122^2 .

It is an emirp because it is prime and its reverse (905551) is a distict prime.

It is a cyclic number.

It is not a de Polignac number, because 155509 - 2³ = 155501 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (155501) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 77754 + 77755.

It is an arithmetic number, because the mean of its divisors is an integer number (77755).

2¹⁵⁵⁵⁰⁹ is an apocalyptic number.

It is an amenable number.

155509 is a deficient number, since it is larger than the sum of its proper divisors (1).

155509 is an equidigital number, since it uses as much as digits as its factorization.

155509 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 1125, while the sum is 25.

The square root of 155509 is about 394.3462945179. The cubic root of 155509 is about 53.7755890416.

The spelling of 155509 in words is "one hundred fifty-five thousand, five hundred nine".