121645 has 4 divisors (see below), whose sum is σ = 145980. Its totient is φ = 97312.

The previous prime is 121637. The next prime is 121661. The reversal of 121645 is 546121.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 546121 = 739².

It can be written as a sum of positive squares in 2 ways, for example, as 72361 + 49284 = 269^2 + 222^2 .

It is a cyclic number.

It is not a de Polignac number, because 121645 - 2³ = 121637 is a prime.

It is a super-3 number, since 3×121645³ = 5400127861233375, which contains 333 as substring.

It is a congruent number.

It is an unprimeable number.

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, 12160 + ... + 12169.

It is an arithmetic number, because the mean of its divisors is an integer number (36495).

2¹²¹⁶⁴⁵ is an apocalyptic number.

It is an amenable number.

121645 is a deficient number, since it is larger than the sum of its proper divisors (24335).

121645 is an equidigital number, since it uses as much as digits as its factorization.

121645 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24334.

The product of its digits is 240, while the sum is 19.

The square root of 121645 is about 348.7764326901. The cubic root of 121645 is about 49.5486037588.

Adding to 121645 its reverse (546121), we get a palindrome (667766).

The spelling of 121645 in words is "one hundred twenty-one thousand, six hundred forty-five".