121855989 has 4 divisors (see below), whose sum is σ = 162474656. Its totient is φ = 81237324.

The previous prime is 121855967. The next prime is 121855991. The reversal of 121855989 is 989558121.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 121855989 - 2⁸ = 121855733 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 (121855919) 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, 20309329 + ... + 20309334.

It is an arithmetic number, because the mean of its divisors is an integer number (40618664).

Almost surely, 2^121855989 is an apocalyptic number.

It is an amenable number.

121855989 is a deficient number, since it is larger than the sum of its proper divisors (40618667).

121855989 is an equidigital number, since it uses as much as digits as its factorization.

121855989 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 40618666.

The product of its digits is 259200, while the sum is 48.

The square root of 121855989 is about 11038.8400205819. The cubic root of 121855989 is about 495.7723398614.

The spelling of 121855989 in words is "one hundred twenty-one million, eight hundred fifty-five thousand, nine hundred eighty-nine".