21011222121 has 8 divisors (see below), whose sum is σ = 28140591360. Its totient is φ = 13944667152.

The previous prime is 21011222101. The next prime is 21011222149. The reversal of 21011222121 is 12122211012.

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

It is not a de Polignac number, because 21011222121 - 2¹⁰ = 21011221097 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21011222121.

It is not an unprimeable number, because it can be changed into a prime (21011222101) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 15702786 + ... + 15704123.

It is an arithmetic number, because the mean of its divisors is an integer number (3517573920).

Almost surely, 2^21011222121 is an apocalyptic number.

It is an amenable number.

21011222121 is a deficient number, since it is larger than the sum of its proper divisors (7129369239).

21011222121 is a wasteful number, since it uses less digits than its factorization.

21011222121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 31407135.

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

Adding to 21011222121 its reverse (12122211012), we get a palindrome (33133433133).

The spelling of 21011222121 in words is "twenty-one billion, eleven million, two hundred twenty-two thousand, one hundred twenty-one".