181212121 has 4 divisors (see below), whose sum is σ = 181322752. Its totient is φ = 181101492.

The previous prime is 181212113. The next prime is 181212127. The reversal of 181212121 is 121212181.

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 a cyclic number.

It is not a de Polignac number, because 181212121 - 2³ = 181212113 is a prime.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (181212127) 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, 52821 + ... + 56146.

It is an arithmetic number, because the mean of its divisors is an integer number (45330688).

Almost surely, 2^181212121 is an apocalyptic number.

It is an amenable number.

181212121 is a deficient number, since it is larger than the sum of its proper divisors (110631).

181212121 is a wasteful number, since it uses less digits than its factorization.

181212121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 110630.

The product of its digits is 64, while the sum is 19.

The square root of 181212121 is about 13461.5051535852. The cubic root of 181212121 is about 565.8861714266.

The spelling of 181212121 in words is "one hundred eighty-one million, two hundred twelve thousand, one hundred twenty-one".