18808121 has 4 divisors (see below), whose sum is σ = 18934500. Its totient is φ = 18681744.

The previous prime is 18808117. The next prime is 18808133. The reversal of 18808121 is 12180881.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 2446096 + 16362025 = 1564^2 + 4045^2 .

It is a cyclic number.

It is not a de Polignac number, because 18808121 - 2² = 18808117 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (18808151) 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, 62966 + ... + 63263.

It is an arithmetic number, because the mean of its divisors is an integer number (4733625).

Almost surely, 2^18808121 is an apocalyptic number.

It is an amenable number.

18808121 is a deficient number, since it is larger than the sum of its proper divisors (126379).

18808121 is a wasteful number, since it uses less digits than its factorization.

18808121 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 126378.

The product of its (nonzero) digits is 1024, while the sum is 29.

The square root of 18808121 is about 4336.8330611173. The cubic root of 18808121 is about 265.9388603900.

It can be divided in two parts, 1880 and 8121, that added together give a palindrome (10001).

The spelling of 18808121 in words is "eighteen million, eight hundred eight thousand, one hundred twenty-one".