123561 has 6 divisors (see below), whose sum is σ = 178490. Its totient is φ = 82368.

The previous prime is 123553. The next prime is 123581. The reversal of 123561 is 165321.

It can be written as a sum of positive squares in only one way, i.e., 99225 + 24336 = 315^2 + 156^2 .

It is not a de Polignac number, because 123561 - 2³ = 123553 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (123551) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 6856 + ... + 6873.

2¹²³⁵⁶¹ is an apocalyptic number.

It is an amenable number.

123561 is a deficient number, since it is larger than the sum of its proper divisors (54929).

123561 is a wasteful number, since it uses less digits than its factorization.

It is an anagram of its base 8 representation: 123561 = (361251)₈.

123561 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13735 (or 13732 counting only the distinct ones).

The product of its digits is 180, while the sum is 18.

The square root of 123561 is about 351.5124464368. The cubic root of 123561 is about 49.8073923318.

Adding to 123561 its reverse (165321), we get a palindrome (288882).

It can be divided in two parts, 1235 and 61, that added together give a 4-th power (1296 = 6⁴).

The spelling of 123561 in words is "one hundred twenty-three thousand, five hundred sixty-one".