216921121 has 8 divisors (see below), whose sum is σ = 227525760. Its totient is φ = 206566128.

The previous prime is 216921113. The next prime is 216921127. The reversal of 216921121 is 121129612.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 216921121 - 2³ = 216921113 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (216921127) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 60631 + ... + 64108.

It is an arithmetic number, because the mean of its divisors is an integer number (28440720).

Almost surely, 2^216921121 is an apocalyptic number.

It is an amenable number.

216921121 is a deficient number, since it is larger than the sum of its proper divisors (10604639).

216921121 is a wasteful number, since it uses less digits than its factorization.

216921121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 124823.

The product of its digits is 432, while the sum is 25.

The square root of 216921121 is about 14728.2422915975. The cubic root of 216921121 is about 600.8516803105.

It can be divided in two parts, 21 and 6921121, that multiplied together give a palindrome (145343541).

The spelling of 216921121 in words is "two hundred sixteen million, nine hundred twenty-one thousand, one hundred twenty-one".