123649 has 4 divisors (see below), whose sum is σ = 126036. Its totient is φ = 121264.

The previous prime is 123637. The next prime is 123653. The reversal of 123649 is 946321.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 946321 = 41 ⋅23081.

It can be written as a sum of positive squares in 2 ways, for example, as 66049 + 57600 = 257^2 + 240^2 .

It is a de Polignac number, because none of the positive numbers 2^k-123649 is a prime.

It is a Duffinian number.

123649 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (123619) 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, 1114 + ... + 1219.

It is an arithmetic number, because the mean of its divisors is an integer number (31509).

2¹²³⁶⁴⁹ is an apocalyptic number.

It is an amenable number.

123649 is a deficient number, since it is larger than the sum of its proper divisors (2387).

123649 is an equidigital number, since it uses as much as digits as its factorization.

123649 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2386.

The product of its digits is 1296, while the sum is 25.

The square root of 123649 is about 351.6375975347. The cubic root of 123649 is about 49.8192137814.

The spelling of 123649 in words is "one hundred twenty-three thousand, six hundred forty-nine".