11212121021 has 4 divisors (see below), whose sum is σ = 11237661600. Its totient is φ = 11186580444.

The previous prime is 11212121017. The next prime is 11212121023. The reversal of 11212121021 is 12012121211.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 11212121021 - 2² = 11212121017 is a prime.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 11212120987 and 11212121005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (11212121023) 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 3 ways as a sum of consecutive naturals, for example, 12769631 + ... + 12770508.

It is an arithmetic number, because the mean of its divisors is an integer number (2809415400).

Almost surely, 2^11212121021 is an apocalyptic number.

It is an amenable number.

11212121021 is a deficient number, since it is larger than the sum of its proper divisors (25540579).

11212121021 is an equidigital number, since it uses as much as digits as its factorization.

11212121021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 25540578.

The product of its (nonzero) digits is 16, while the sum is 14.

Adding to 11212121021 its reverse (12012121211), we get a palindrome (23224242232).

The spelling of 11212121021 in words is "eleven billion, two hundred twelve million, one hundred twenty-one thousand, twenty-one".