121665787 has 4 divisors (see below), whose sum is σ = 128822616. Its totient is φ = 114508960.

The previous prime is 121665773. The next prime is 121665809. The reversal of 121665787 is 787566121.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 121665787 - 2¹¹ = 121663739 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (121665757) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3578389 + ... + 3578422.

It is an arithmetic number, because the mean of its divisors is an integer number (32205654).

Almost surely, 2^121665787 is an apocalyptic number.

121665787 is a gapful number since it is divisible by the number (17) formed by its first and last digit.

121665787 is a deficient number, since it is larger than the sum of its proper divisors (7156829).

121665787 is an equidigital number, since it uses as much as digits as its factorization.

121665787 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7156828.

The product of its digits is 141120, while the sum is 43.

The square root of 121665787 is about 11030.2215299603. The cubic root of 121665787 is about 495.5142592756.

The spelling of 121665787 in words is "one hundred twenty-one million, six hundred sixty-five thousand, seven hundred eighty-seven".