123639 has 4 divisors (see below), whose sum is σ = 164856. Its totient is φ = 82424.

The previous prime is 123637. The next prime is 123653. The reversal of 123639 is 936321.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 936321 = 3 ⋅312107.

It is a cyclic number.

It is not a de Polignac number, because 123639 - 2¹ = 123637 is a prime.

It is a D-number.

123639 is a lucky number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (123631) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 20604 + ... + 20609.

It is an arithmetic number, because the mean of its divisors is an integer number (41214).

2¹²³⁶³⁹ is an apocalyptic number.

123639 is a deficient number, since it is larger than the sum of its proper divisors (41217).

123639 is an equidigital number, since it uses as much as digits as its factorization.

123639 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41216.

The product of its digits is 972, while the sum is 24.

The square root of 123639 is about 351.6233780624. The cubic root of 123639 is about 49.8178707173.

It can be divided in two parts, 1236 and 39, that added together give a triangular number (1275 = T₅₀).

The spelling of 123639 in words is "one hundred twenty-three thousand, six hundred thirty-nine".