21203212111 has 4 divisors (see below), whose sum is σ = 21365068824. Its totient is φ = 21041355400.

The previous prime is 21203212109. The next prime is 21203212139. The reversal of 21203212111 is 11121230212.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21203212111 - 2¹ = 21203212109 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21203213111) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 80928160 + ... + 80928421.

It is an arithmetic number, because the mean of its divisors is an integer number (5341267206).

Almost surely, 2^21203212111 is an apocalyptic number.

21203212111 is a deficient number, since it is larger than the sum of its proper divisors (161856713).

21203212111 is a wasteful number, since it uses less digits than its factorization.

21203212111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 161856712.

The product of its (nonzero) digits is 48, while the sum is 16.

Adding to 21203212111 its reverse (11121230212), we get a palindrome (32324442323).

The spelling of 21203212111 in words is "twenty-one billion, two hundred three million, two hundred twelve thousand, one hundred eleven".