121821342655 has 4 divisors (see below), whose sum is σ = 146185611192. Its totient is φ = 97457074120.

The previous prime is 121821342653. The next prime is 121821342719. The reversal of 121821342655 is 556243128121.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 556243128121 = 1747 ⋅318399043.

It is not a de Polignac number, because 121821342655 - 2¹ = 121821342653 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (121821342653) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12182134261 + ... + 12182134270.

It is an arithmetic number, because the mean of its divisors is an integer number (36546402798).

Almost surely, 2^121821342655 is an apocalyptic number.

121821342655 is a deficient number, since it is larger than the sum of its proper divisors (24364268537).

121821342655 is an equidigital number, since it uses as much as digits as its factorization.

121821342655 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24364268536.

The product of its digits is 115200, while the sum is 40.

The spelling of 121821342655 in words is "one hundred twenty-one billion, eight hundred twenty-one million, three hundred forty-two thousand, six hundred fifty-five".