155405 has 4 divisors (see below), whose sum is σ = 186492. Its totient is φ = 124320.

The previous prime is 155399. The next prime is 155413. The reversal of 155405 is 504551.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 504551 = 23 ⋅21937.

It can be written as a sum of positive squares in 2 ways, for example, as 51076 + 104329 = 226^2 + 323^2 .

It is not a de Polignac number, because 155405 - 2¹⁴ = 139021 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 15536 + ... + 15545.

It is an arithmetic number, because the mean of its divisors is an integer number (46623).

2¹⁵⁵⁴⁰⁵ is an apocalyptic number.

It is an amenable number.

155405 is a deficient number, since it is larger than the sum of its proper divisors (31087).

155405 is an equidigital number, since it uses as much as digits as its factorization.

155405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 31086.

The product of its (nonzero) digits is 500, while the sum is 20.

The square root of 155405 is about 394.2144086661. The cubic root of 155405 is about 53.7635985063.

Adding to 155405 its reverse (504551), we get a palindrome (659956).

The spelling of 155405 in words is "one hundred fifty-five thousand, four hundred five".