12121855 has 16 divisors (see below), whose sum is σ = 15422400. Its totient is φ = 9130240.

The previous prime is 12121831. The next prime is 12121871. The reversal of 12121855 is 55812121.

It is not a de Polignac number, because 12121855 - 2¹⁵ = 12089087 is a prime.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4926 + ... + 6964.

It is an arithmetic number, because the mean of its divisors is an integer number (963900).

Almost surely, 2^12121855 is an apocalyptic number.

12121855 is a deficient number, since it is larger than the sum of its proper divisors (3300545).

12121855 is a wasteful number, since it uses less digits than its factorization.

12121855 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2114.

The product of its digits is 800, while the sum is 25.

The square root of 12121855 is about 3481.6454443266. The cubic root of 12121855 is about 229.7151798903.

Adding to 12121855 its reverse (55812121), we get a palindrome (67933976).

It can be divided in two parts, 1212 and 1855, that multiplied together give a triangular number (2248260 = T₂₁₂₀).

The spelling of 12121855 in words is "twelve million, one hundred twenty-one thousand, eight hundred fifty-five".