21212021111 has 16 divisors (see below), whose sum is σ = 21918376896. Its totient is φ = 20520900000.

The previous prime is 21212021071. The next prime is 21212021123. The reversal of 21212021111 is 11112021212.

It is not a de Polignac number, because 21212021111 - 2¹⁰ = 21212020087 is a prime.

It is a super-2 number, since 2×21212021111² (a number of 21 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 (21212021161) 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, 140476886 + ... + 140477036.

It is an arithmetic number, because the mean of its divisors is an integer number (1369898556).

Almost surely, 2^21212021111 is an apocalyptic number.

21212021111 is a deficient number, since it is larger than the sum of its proper divisors (706355785).

21212021111 is an frugal number, since it uses more digits than its factorization.

21212021111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 615 (or 313 counting only the distinct ones).

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

Adding to 21212021111 its reverse (11112021212), we get a palindrome (32324042323).

The spelling of 21212021111 in words is "twenty-one billion, two hundred twelve million, twenty-one thousand, one hundred eleven".