121815 has 12 divisors (see below), whose sum is σ = 211224. Its totient is φ = 64944.

The previous prime is 121789. The next prime is 121843. The reversal of 121815 is 518121.

121815 is nontrivially palindromic in base 7.

It is not a de Polignac number, because 121815 - 2⁷ = 121687 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 1309 + ... + 1398.

It is an arithmetic number, because the mean of its divisors is an integer number (17602).

121815 is a Friedman number, since it can be written as 8121*15, using all its digits and the basic arithmetic operations.

2¹²¹⁸¹⁵ is an apocalyptic number.

121815 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

121815 is a deficient number, since it is larger than the sum of its proper divisors (89409).

121815 is a wasteful number, since it uses less digits than its factorization.

121815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2718 (or 2715 counting only the distinct ones).

The product of its digits is 80, while the sum is 18.

The square root of 121815 is about 349.0200567303. The cubic root of 121815 is about 49.5716745572.

Adding to 121815 its reverse (518121), we get a palindrome (639936).

The spelling of 121815 in words is "one hundred twenty-one thousand, eight hundred fifteen".