121989155 has 4 divisors (see below), whose sum is σ = 146386992.
Its totient is φ = 97591320.
The previous prime is 121989149. The next prime is 121989163. The reversal of 121989155 is 551989121.
It is a semiprime because it is the product of two primes.
It is not a de Polignac number, because 121989155 - 226 = 54880291 is a prime.
It is a super-2 number, since 2×1219891552 = 29762707875228050, which contains 22 as substring.
It is a Duffinian number.
It is an unprimeable number.
It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 12198911 + ... + 12198920.
It is an arithmetic number, because the mean of its divisors is an integer number (36596748).
Almost surely, 2121989155 is an apocalyptic number.
121989155 is a deficient number, since it is larger than the sum of its proper divisors (24397837).
121989155 is an equidigital number, since it uses as much as digits as its factorization.
121989155 is an evil number, because the sum of its binary digits is even.
The sum of its prime factors is 24397836.
The product of its digits is 32400, while the sum is 41.
The square root of 121989155 is about 11044.8700761937.
The cubic root of 121989155 is about 495.9528698606.
The spelling of 121989155 in words is "one hundred twenty-one million, nine hundred eighty-nine thousand, one hundred fifty-five".