21021221121 has 16 divisors (see below), whose sum is σ = 29507688000. Its totient is φ = 13274661888.

The previous prime is 21021221119. The next prime is 21021221141. The reversal of 21021221121 is 12112212012.

It is not a de Polignac number, because 21021221121 - 2¹ = 21021221119 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21021221121.

It is not an unprimeable number, because it can be changed into a prime (21021221141) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 450705 + ... + 495153.

It is an arithmetic number, because the mean of its divisors is an integer number (1844230500).

Almost surely, 2^21021221121 is an apocalyptic number.

It is an amenable number.

21021221121 is a deficient number, since it is larger than the sum of its proper divisors (8486466879).

21021221121 is a wasteful number, since it uses less digits than its factorization.

21021221121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 52768.

The product of its (nonzero) digits is 32, while the sum is 15.

Adding to 21021221121 its reverse (12112212012), we get a palindrome (33133433133).

The spelling of 21021221121 in words is "twenty-one billion, twenty-one million, two hundred twenty-one thousand, one hundred twenty-one".