21121011212111 has 4 divisors (see below), whose sum is σ = 21307922815872. Its totient is φ = 20934099608352.

The previous prime is 21121011212099. The next prime is 21121011212117. The reversal of 21121011212111 is 11121211012112.

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 21121011212111 - 2³⁸ = 20846133305167 is a prime.

It is a super-2 number, since 2×21121011212111² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 21121011212111.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121011212117) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (29) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 93455801711 + ... + 93455801936.

It is an arithmetic number, because the mean of its divisors is an integer number (5326980703968).

Almost surely, 2^{21121011212111} is an apocalyptic number.

21121011212111 is a deficient number, since it is larger than the sum of its proper divisors (186911603761).

21121011212111 is a wasteful number, since it uses less digits than its factorization.

21121011212111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 186911603760.

The product of its (nonzero) digits is 16, while the sum is 17.

Adding to 21121011212111 its reverse (11121211012112), we get a palindrome (32242222224223).

The spelling of 21121011212111 in words is "twenty-one trillion, one hundred twenty-one billion, eleven million, two hundred twelve thousand, one hundred eleven".