21010121211111 has 4 divisors (see below), whose sum is σ = 28013494948152. Its totient is φ = 14006747474072.

The previous prime is 21010121211109. The next prime is 21010121211133. The reversal of 21010121211111 is 11111212101012.

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 21010121211111 - 2¹ = 21010121211109 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21010121211181) 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, 3501686868516 + ... + 3501686868521.

It is an arithmetic number, because the mean of its divisors is an integer number (7003373737038).

Almost surely, 2^{21010121211111} is an apocalyptic number.

21010121211111 is a deficient number, since it is larger than the sum of its proper divisors (7003373737041).

21010121211111 is an equidigital number, since it uses as much as digits as its factorization.

21010121211111 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7003373737040.

The product of its (nonzero) digits is 8, while the sum is 15.

Adding to 21010121211111 its reverse (11111212101012), we get a palindrome (32121333312123).

It can be divided in two parts, 21010 and 121211111, that added together give a palindrome (121232121).

The spelling of 21010121211111 in words is "twenty-one trillion, ten billion, one hundred twenty-one million, two hundred eleven thousand, one hundred eleven".