121665 has 8 divisors (see below), whose sum is σ = 194688. Its totient is φ = 64880.

The previous prime is 121661. The next prime is 121687. The reversal of 121665 is 566121.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 121665 - 2² = 121661 is a prime.

It is an Ulam number.

It is not an unprimeable number, because it can be changed into a prime (121661) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 4041 + ... + 4070.

It is an arithmetic number, because the mean of its divisors is an integer number (24336).

2¹²¹⁶⁶⁵ is an apocalyptic number.

121665 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

121665 is a deficient number, since it is larger than the sum of its proper divisors (73023).

121665 is an equidigital number, since it uses as much as digits as its factorization.

121665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8119.

The product of its digits is 360, while the sum is 21.

The square root of 121665 is about 348.8051031737. The cubic root of 121665 is about 49.5513190855.

Adding to 121665 its reverse (566121), we get a palindrome (687786).

The spelling of 121665 in words is "one hundred twenty-one thousand, six hundred sixty-five".