121689 has 8 divisors (see below), whose sum is σ = 180320. Its totient is φ = 81108.

The previous prime is 121687. The next prime is 121697. The reversal of 121689 is 986121.

It is not a de Polignac number, because 121689 - 2¹ = 121687 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (27), and also a Moran number because the ratio is a prime number: 4507 = 121689 / (1 + 2 + 1 + 6 + 8 + 9).

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (121687) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2227 + ... + 2280.

It is an arithmetic number, because the mean of its divisors is an integer number (22540).

2¹²¹⁶⁸⁹ is an apocalyptic number.

It is an amenable number.

121689 is a deficient number, since it is larger than the sum of its proper divisors (58631).

121689 is an equidigital number, since it uses as much as digits as its factorization.

121689 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4516 (or 4510 counting only the distinct ones).

The product of its digits is 864, while the sum is 27.

The square root of 121689 is about 348.8395046436. The cubic root of 121689 is about 49.5545770849.

The spelling of 121689 in words is "one hundred twenty-one thousand, six hundred eighty-nine".