21011221212121 has 8 divisors (see below), whose sum is σ = 24012876682880. Its totient is φ = 18009578851488.

The previous prime is 21011221212101. The next prime is 21011221212169. The reversal of 21011221212121 is 12121212211012.

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 21011221212121 - 2¹¹ = 21011221210073 is a prime.

It is a Duffinian number.

21011221212121 is a modest number, since divided by 21212121 gives 210112 as remainder.

It is not an unprimeable number, because it can be changed into a prime (21011221212101) 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, 437500 + ... + 6497218.

It is an arithmetic number, because the mean of its divisors is an integer number (3001609585360).

Almost surely, 2^{21011221212121} is an apocalyptic number.

It is an amenable number.

21011221212121 is a deficient number, since it is larger than the sum of its proper divisors (3001655470759).

21011221212121 is an equidigital number, since it uses as much as digits as its factorization.

21011221212121 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 6555063.

The product of its (nonzero) digits is 64, while the sum is 19.

Adding to 21011221212121 its reverse (12121212211012), we get a palindrome (33132433423133).

The spelling of 21011221212121 in words is "twenty-one trillion, eleven billion, two hundred twenty-one million, two hundred twelve thousand, one hundred twenty-one".