121405 has 4 divisors (see below), whose sum is σ = 145692. Its totient is φ = 97120.
The previous prime is 121403. The next prime is 121421. The reversal of 121405 is 504121.
It is a semiprime because it is the product of two primes.
It can be written as a sum of positive squares in 2 ways, for example, as 86436 + 34969 = 294^2 + 187^2 .
It is not a de Polignac number, because 121405 - 21 = 121403 is a prime.
It is a Duffinian number.
It is a congruent number.
It is not an unprimeable number, because it can be changed into a prime (121403) 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, 12136 + ... + 12145.
It is an arithmetic number, because the mean of its divisors is an integer number (36423).
2121405 is an apocalyptic number.
It is an amenable number.
121405 is a deficient number, since it is larger than the sum of its proper divisors (24287).
121405 is an equidigital number, since it uses as much as digits as its factorization.
121405 is an odious number, because the sum of its binary digits is odd.
The sum of its prime factors is 24286.
The product of its (nonzero) digits is 40, while the sum is 13.
The square root of 121405 is about 348.4322028745. The cubic root of 121405 is about 49.5159965985.
Adding to 121405 its reverse (504121), we get a palindrome (625526).
The spelling of 121405 in words is "one hundred twenty-one thousand, four hundred five".
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