121990 has 16 divisors (see below), whose sum is σ = 239760. Its totient is φ = 44320.

The previous prime is 121967. The next prime is 121993. The reversal of 121990 is 99121.

It is a Harshad number since it is a multiple of its sum of digits (22).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (121993) by changing a digit.

121990 is an untouchable number, because it is not equal to the sum of proper divisors of any number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 445 + ... + 664.

It is an arithmetic number, because the mean of its divisors is an integer number (14985).

2¹²¹⁹⁹⁰ is an apocalyptic number.

121990 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

121990 is a deficient number, since it is larger than the sum of its proper divisors (117770).

121990 is a wasteful number, since it uses less digits than its factorization.

121990 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1127.

The product of its (nonzero) digits is 162, while the sum is 22.

The square root of 121990 is about 349.2706686798. The cubic root of 121990 is about 49.5954014988.

It can be divided in two parts, 121 and 990, that added together give a palindrome (1111).

The spelling of 121990 in words is "one hundred twenty-one thousand, nine hundred ninety".