218020121 has 16 divisors (see below), whose sum is σ = 255296448. Its totient is φ = 183974400.

The previous prime is 218020109. The next prime is 218020123. The reversal of 218020121 is 121020812.

It is a happy number.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-218020121 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (17).

It is a self number, because there is not a number n which added to its sum of digits gives 218020121.

It is not an unprimeable number, because it can be changed into a prime (218020123) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 5666 + ... + 21636.

It is an arithmetic number, because the mean of its divisors is an integer number (15956028).

Almost surely, 2^218020121 is an apocalyptic number.

It is an amenable number.

218020121 is a deficient number, since it is larger than the sum of its proper divisors (37276327).

218020121 is a wasteful number, since it uses less digits than its factorization.

218020121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16072.

The product of its (nonzero) digits is 64, while the sum is 17.

The square root of 218020121 is about 14765.5044275500. The cubic root of 218020121 is about 601.8646813433.

Adding to 218020121 its reverse (121020812), we get a palindrome (339040933).

The spelling of 218020121 in words is "two hundred eighteen million, twenty thousand, one hundred twenty-one".