121905 has 40 divisors (see below), whose sum is σ = 255552. Its totient is φ = 54432.

The previous prime is 121889. The next prime is 121909. The reversal of 121905 is 509121.

121905 = 9³ + 10³ + ... + 26³.

It is not a de Polignac number, because 121905 - 2⁴ = 121889 is a prime.

It is not an unprimeable number, because it can be changed into a prime (121909) by changing a digit.

It is a polite number, since it can be written in 39 ways as a sum of consecutive naturals, for example, 2814 + ... + 2856.

2¹²¹⁹⁰⁵ is an apocalyptic number.

121905 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

121905 is an abundant number, since it is smaller than the sum of its proper divisors (133647).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

121905 is an equidigital number, since it uses as much as digits as its factorization.

121905 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 67 (or 58 counting only the distinct ones).

The product of its (nonzero) digits is 90, while the sum is 18.

The square root of 121905 is about 349.1489653429. The cubic root of 121905 is about 49.5838798204.

The spelling of 121905 in words is "one hundred twenty-one thousand, nine hundred five".