121809665 has 16 divisors (see below), whose sum is σ = 157144320. Its totient is φ = 90351360.

The previous prime is 121809643. The next prime is 121809673. The reversal of 121809665 is 566908121.

It is not a de Polignac number, because 121809665 - 2⁸ = 121809409 is a prime.

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 15 ways as a sum of consecutive naturals, for example, 9176 + ... + 18105.

It is an arithmetic number, because the mean of its divisors is an integer number (9821520).

Almost surely, 2^121809665 is an apocalyptic number.

It is an amenable number.

121809665 is a deficient number, since it is larger than the sum of its proper divisors (35334655).

121809665 is a wasteful number, since it uses less digits than its factorization.

121809665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27352.

The product of its (nonzero) digits is 25920, while the sum is 38.

The square root of 121809665 is about 11036.7415934233. The cubic root of 121809665 is about 495.7095086760.

The spelling of 121809665 in words is "one hundred twenty-one million, eight hundred nine thousand, six hundred sixty-five".