121890 has 32 divisors (see below), whose sum is σ = 311040. Its totient is φ = 30464.

The previous prime is 121889. The next prime is 121909. The reversal of 121890 is 98121.

It is an alternating number because its digits alternate between odd and even.

It is a Curzon number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 391 + ... + 629.

It is an arithmetic number, because the mean of its divisors is an integer number (9720).

2¹²¹⁸⁹⁰ is an apocalyptic number.

121890 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is a practical number, because each smaller number is the sum of distinct divisors of 121890, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (155520).

121890 is an abundant number, since it is smaller than the sum of its proper divisors (189150).

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

121890 is a wasteful number, since it uses less digits than its factorization.

121890 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 266.

The product of its (nonzero) digits is 144, while the sum is 21.

The square root of 121890 is about 349.1274838795. The cubic root of 121890 is about 49.5818460271.

The spelling of 121890 in words is "one hundred twenty-one thousand, eight hundred ninety".