155611 has 4 divisors (see below), whose sum is σ = 158224. Its totient is φ = 153000.

The previous prime is 155609. The next prime is 155621. The reversal of 155611 is 116551.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 116551 = 29 ⋅4019.

It is a cyclic number.

It is not a de Polignac number, because 155611 - 2¹ = 155609 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (155621) 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 in 3 ways as a sum of consecutive naturals, for example, 1215 + ... + 1336.

It is an arithmetic number, because the mean of its divisors is an integer number (39556).

2¹⁵⁵⁶¹¹ is an apocalyptic number.

155611 is a deficient number, since it is larger than the sum of its proper divisors (2613).

155611 is an equidigital number, since it uses as much as digits as its factorization.

155611 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2612.

The product of its digits is 150, while the sum is 19.

The square root of 155611 is about 394.4756012734. The cubic root of 155611 is about 53.7873437981.

Subtracting from 155611 its reverse (116551), we obtain a triangular number (39060 = T₂₇₉).

The spelling of 155611 in words is "one hundred fifty-five thousand, six hundred eleven".