21121122221111 has 16 divisors (see below), whose sum is σ = 24426672657408. Its totient is φ = 18049265251200.

The previous prime is 21121122221081. The next prime is 21121122221167. The reversal of 21121122221111 is 11112222112112.

It is a happy number.

It is a cyclic number.

It is not a de Polignac number, because 21121122221111 - 2¹⁴ = 21121122204727 is a prime.

It is a super-2 number, since 2×21121122221111² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121122221191) 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, 69482855 + ... + 69786168.

It is an arithmetic number, because the mean of its divisors is an integer number (1526667041088).

Almost surely, 2^{21121122221111} is an apocalyptic number.

21121122221111 is a deficient number, since it is larger than the sum of its proper divisors (3305550436297).

21121122221111 is a wasteful number, since it uses less digits than its factorization.

21121122221111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 139269862.

The product of its digits is 64, while the sum is 20.

Adding to 21121122221111 its reverse (11112222112112), we get a palindrome (32233344333223).

The spelling of 21121122221111 in words is "twenty-one trillion, one hundred twenty-one billion, one hundred twenty-two million, two hundred twenty-one thousand, one hundred eleven".