121729 has 4 divisors (see below), whose sum is σ = 124740. Its totient is φ = 118720.

The previous prime is 121727. The next prime is 121763. The reversal of 121729 is 927121.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 927121 = 13 ⋅71317.

It can be written as a sum of positive squares in 2 ways, for example, as 2704 + 119025 = 52^2 + 345^2 .

It is a cyclic number.

It is not a de Polignac number, because 121729 - 2¹ = 121727 is a prime.

It is an Ulam number.

It is a Duffinian number.

121729 is a lucky number.

It is not an unprimeable number, because it can be changed into a prime (121721) 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, 1444 + ... + 1525.

It is an arithmetic number, because the mean of its divisors is an integer number (31185).

2¹²¹⁷²⁹ is an apocalyptic number.

It is an amenable number.

121729 is a deficient number, since it is larger than the sum of its proper divisors (3011).

121729 is an equidigital number, since it uses as much as digits as its factorization.

121729 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3010.

The product of its digits is 252, while the sum is 22.

The square root of 121729 is about 348.8968328890. The cubic root of 121729 is about 49.5600061320.

It can be divided in two parts, 121 and 729, that multiplied together give a square (88209 = 297²).

The spelling of 121729 in words is "one hundred twenty-one thousand, seven hundred twenty-nine".