121243155 has 16 divisors (see below), whose sum is σ = 211624704. Its totient is φ = 58784480.

The previous prime is 121243153. The next prime is 121243183. The reversal of 121243155 is 551342121.

It is a happy number.

It is not a de Polignac number, because 121243155 - 2¹ = 121243153 is a prime.

It is not an unprimeable number, because it can be changed into a prime (121243151) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 367239 + ... + 367568.

It is an arithmetic number, because the mean of its divisors is an integer number (13226544).

Almost surely, 2^121243155 is an apocalyptic number.

121243155 is a gapful number since it is divisible by the number (15) formed by its first and last digit.

121243155 is a deficient number, since it is larger than the sum of its proper divisors (90381549).

121243155 is a wasteful number, since it uses less digits than its factorization.

121243155 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 734826.

The product of its digits is 1200, while the sum is 24.

The square root of 121243155 is about 11011.0469529468. The cubic root of 121243155 is about 494.9398355608.

Adding to 121243155 its reverse (551342121), we get a palindrome (672585276).

The spelling of 121243155 in words is "one hundred twenty-one million, two hundred forty-three thousand, one hundred fifty-five".