21212121111009 has 4 divisors (see below), whose sum is σ = 28282828148016. Its totient is φ = 14141414074004.

The previous prime is 21212121110981. The next prime is 21212121111059. The reversal of 21212121111009 is 90011112121212.

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 21212121111009 - 2⁸ = 21212121110753 is a prime.

It is a super-2 number, since 2×21212121111009² (a number of 27 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21212121111009.

It is not an unprimeable number, because it can be changed into a prime (21212121111059) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3535353518499 + ... + 3535353518504.

It is an arithmetic number, because the mean of its divisors is an integer number (7070707037004).

Almost surely, 2^{21212121111009} is an apocalyptic number.

It is an amenable number.

21212121111009 is a deficient number, since it is larger than the sum of its proper divisors (7070707037007).

21212121111009 is an equidigital number, since it uses as much as digits as its factorization.

21212121111009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7070707037006.

The product of its (nonzero) digits is 144, while the sum is 24.

The spelling of 21212121111009 in words is "twenty-one trillion, two hundred twelve billion, one hundred twenty-one million, one hundred eleven thousand, nine".