121205405 has 4 divisors (see below), whose sum is σ = 145446492. Its totient is φ = 96964320.

The previous prime is 121205401. The next prime is 121205429. The reversal of 121205405 is 504502121.

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 65060356 + 56145049 = 8066^2 + 7493^2 .

It is not a de Polignac number, because 121205405 - 2² = 121205401 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 (121205401) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12120536 + ... + 12120545.

It is an arithmetic number, because the mean of its divisors is an integer number (36361623).

Almost surely, 2^121205405 is an apocalyptic number.

It is an amenable number.

121205405 is a deficient number, since it is larger than the sum of its proper divisors (24241087).

121205405 is an equidigital number, since it uses as much as digits as its factorization.

121205405 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 24241086.

The product of its (nonzero) digits is 400, while the sum is 20.

The square root of 121205405 is about 11009.3326319083. The cubic root of 121205405 is about 494.8884624386. Note that the first 3 decimals are identical.

Adding to 121205405 its reverse (504502121), we get a palindrome (625707526).

The spelling of 121205405 in words is "one hundred twenty-one million, two hundred five thousand, four hundred five".