218780121 has 16 divisors (see below), whose sum is σ = 334627200. Its totient is φ = 124549248.

The previous prime is 218780119. The next prime is 218780129. The reversal of 218780121 is 121087812.

It is a happy number.

It is not a de Polignac number, because 218780121 - 2¹ = 218780119 is a prime.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (218780129) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 13716 + ... + 25013.

It is an arithmetic number, because the mean of its divisors is an integer number (20914200).

Almost surely, 2^218780121 is an apocalyptic number.

218780121 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

218780121 is a deficient number, since it is larger than the sum of its proper divisors (115847079).

218780121 is a wasteful number, since it uses less digits than its factorization.

218780121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 39008.

The product of its (nonzero) digits is 1792, while the sum is 30.

The square root of 218780121 is about 14791.2176983506. The cubic root of 218780121 is about 602.5632203537.

The spelling of 218780121 in words is "two hundred eighteen million, seven hundred eighty thousand, one hundred twenty-one".