121813 has 4 divisors (see below), whose sum is σ = 122668. Its totient is φ = 120960.

The previous prime is 121789. The next prime is 121843. The reversal of 121813 is 318121.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 318121 = 17 ⋅18713.

It can be written as a sum of positive squares in 2 ways, for example, as 14884 + 106929 = 122^2 + 327^2 .

It is a cyclic number.

It is not a de Polignac number, because 121813 - 2¹³ = 113621 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (121843) 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, 156 + ... + 517.

It is an arithmetic number, because the mean of its divisors is an integer number (30667).

2¹²¹⁸¹³ is an apocalyptic number.

It is an amenable number.

121813 is a deficient number, since it is larger than the sum of its proper divisors (855).

121813 is an equidigital number, since it uses as much as digits as its factorization.

121813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 854.

The product of its digits is 48, while the sum is 16.

The square root of 121813 is about 349.0171915537. The cubic root of 121813 is about 49.5714032609.

Adding to 121813 its reverse (318121), we get a palindrome (439934).

The spelling of 121813 in words is "one hundred twenty-one thousand, eight hundred thirteen".