155813 has 4 divisors (see below), whose sum is σ = 178080. Its totient is φ = 133548.

The previous prime is 155809. The next prime is 155821. The reversal of 155813 is 318551.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4, and also an emirpimes, since its reverse is a distinct semiprime: 318551 = 461 ⋅691.

It is a cyclic number.

It is not a de Polignac number, because 155813 - 2² = 155809 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (155833) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11123 + ... + 11136.

It is an arithmetic number, because the mean of its divisors is an integer number (44520).

2¹⁵⁵⁸¹³ is an apocalyptic number.

It is an amenable number.

155813 is a deficient number, since it is larger than the sum of its proper divisors (22267).

155813 is an equidigital number, since it uses as much as digits as its factorization.

155813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 22266.

The product of its digits is 600, while the sum is 23.

The square root of 155813 is about 394.7315543505. The cubic root of 155813 is about 53.8106076751.

The spelling of 155813 in words is "one hundred fifty-five thousand, eight hundred thirteen".