90121 has 2 divisors, whose sum is σ = 90122.
Its totient is φ = 90120.
The previous prime is 90107. The next prime is 90127. The reversal of 90121 is 12109.
It is a strong prime.
It can be written as a sum of positive squares in only one way, i.e., 90000 + 121 = 300^2 + 11^2
It is an emirp because it is prime and its reverse (12109) is a distict prime.
It is a cyclic number.
It is not a de Polignac number, because 90121 - 25 = 90089 is a prime.
It is an alternating number because its digits alternate between odd and even.
90121 is a lucky number.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (90127) by changing a digit.
It is a pernicious number, because its binary representation contains a prime number (5) of ones.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 45060 + 45061.
It is an arithmetic number, because the mean of its divisors is an integer number (45061).
290121 is an apocalyptic number.
It is an amenable number.
90121 is a deficient number, since it is larger than the sum of its proper divisors (1).
90121 is an equidigital number, since it uses as much as digits as its factorization.
90121 is an odious number, because the sum of its binary digits is odd.
The product of its (nonzero) digits is 18, while the sum is 13.
The square root of 90121 is about 300.2015989298.
The cubic root of 90121 is about 44.8341218044.
The spelling of 90121 in words is "ninety thousand, one hundred twenty-one".