121819665 has 16 divisors (see below), whose sum is σ = 212630976. Its totient is φ = 59064000.

The previous prime is 121819657. The next prime is 121819667. The reversal of 121819665 is 566918121.

It is not a de Polignac number, because 121819665 - 2³ = 121819657 is a prime.

It is not an unprimeable number, because it can be changed into a prime (121819667) by changing a digit.

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, 368986 + ... + 369315.

It is an arithmetic number, because the mean of its divisors is an integer number (13289436).

Almost surely, 2^121819665 is an apocalyptic number.

121819665 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

It is an amenable number.

121819665 is a deficient number, since it is larger than the sum of its proper divisors (90811311).

121819665 is a wasteful number, since it uses less digits than its factorization.

121819665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 738320.

The product of its digits is 25920, while the sum is 39.

The square root of 121819665 is about 11037.1946163869. The cubic root of 121819665 is about 495.7230734438.

The spelling of 121819665 in words is "one hundred twenty-one million, eight hundred nineteen thousand, six hundred sixty-five".