121865 has 4 divisors (see below), whose sum is σ = 146244. Its totient is φ = 97488.

The previous prime is 121853. The next prime is 121867. The reversal of 121865 is 568121.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 568121 = 379 ⋅1499.

It can be written as a sum of positive squares in 2 ways, for example, as 41209 + 80656 = 203^2 + 284^2 .

It is a cyclic number.

It is not a de Polignac number, because 121865 - 2⁸ = 121609 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 121865.

It is not an unprimeable number, because it can be changed into a prime (121867) 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, 12182 + ... + 12191.

It is an arithmetic number, because the mean of its divisors is an integer number (36561).

2¹²¹⁸⁶⁵ is an apocalyptic number.

It is an amenable number.

121865 is a deficient number, since it is larger than the sum of its proper divisors (24379).

121865 is an equidigital number, since it uses as much as digits as its factorization.

121865 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24378.

The product of its digits is 480, while the sum is 23.

The square root of 121865 is about 349.0916785029. The cubic root of 121865 is about 49.5784560009.

Adding to 121865 its reverse (568121), we get a palindrome (689986).

The spelling of 121865 in words is "one hundred twenty-one thousand, eight hundred sixty-five".