121605 has 24 divisors (see below), whose sum is σ = 217056. Its totient is φ = 58080.

The previous prime is 121591. The next prime is 121607. The reversal of 121605 is 506121.

It is not a de Polignac number, because 121605 - 2⁸ = 121349 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (15).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (121607) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1782 + ... + 1848.

It is an arithmetic number, because the mean of its divisors is an integer number (9044).

2¹²¹⁶⁰⁵ is an apocalyptic number.

121605 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

121605 is a deficient number, since it is larger than the sum of its proper divisors (95451).

121605 is a wasteful number, since it uses less digits than its factorization.

121605 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 97 (or 86 counting only the distinct ones).

The product of its (nonzero) digits is 60, while the sum is 15.

The square root of 121605 is about 348.7190846512. The cubic root of 121605 is about 49.5431722123.

Adding to 121605 its reverse (506121), we get a palindrome (627726).

The spelling of 121605 in words is "one hundred twenty-one thousand, six hundred five".