121817 has 4 divisors (see below), whose sum is σ = 123876. Its totient is φ = 119760.

The previous prime is 121789. The next prime is 121843. The reversal of 121817 is 718121.

121817 is nontrivially palindromic in base 15.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 3481 + 118336 = 59^2 + 344^2 .

It is a cyclic number.

It is not a de Polignac number, because 121817 - 2¹² = 117721 is a prime.

It is a Duffinian number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 121817.

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, 938 + ... + 1059.

It is an arithmetic number, because the mean of its divisors is an integer number (30969).

2¹²¹⁸¹⁷ is an apocalyptic number.

It is an amenable number.

121817 is a deficient number, since it is larger than the sum of its proper divisors (2059).

121817 is an equidigital number, since it uses as much as digits as its factorization.

121817 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2058.

The product of its digits is 112, while the sum is 20.

The square root of 121817 is about 349.0229218834. The cubic root of 121817 is about 49.5719458506.

Adding to 121817 its reverse (718121), we get a palindrome (839938).

It can be divided in two parts, 1218 and 17, that multiplied together give a triangular number (20706 = T₂₀₃).

The spelling of 121817 in words is "one hundred twenty-one thousand, eight hundred seventeen".