121999 has 4 divisors (see below), whose sum is σ = 128440. Its totient is φ = 115560.

The previous prime is 121997. The next prime is 122011. The reversal of 121999 is 999121.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 999121 = 191 ⋅5231.

It is a cyclic number.

It is not a de Polignac number, because 121999 - 2¹ = 121997 is a prime.

121999 is a modest number, since divided by 999 gives 121 as remainder.

It is a self number, because there is not a number n which added to its sum of digits gives 121999.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (121993) 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 3 ways as a sum of consecutive naturals, for example, 3192 + ... + 3229.

It is an arithmetic number, because the mean of its divisors is an integer number (32110).

2¹²¹⁹⁹⁹ is an apocalyptic number.

121999 is a gapful number since it is divisible by the number (19) formed by its first and last digit.

121999 is a deficient number, since it is larger than the sum of its proper divisors (6441).

121999 is an equidigital number, since it uses as much as digits as its factorization.

121999 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6440.

The product of its digits is 1458, while the sum is 31.

The square root of 121999 is about 349.2835524327. The cubic root of 121999 is about 49.5966211278.

The spelling of 121999 in words is "one hundred twenty-one thousand, nine hundred ninety-nine".