21211212012021 has 24 divisors (see below), whose sum is σ = 30808673521080. Its totient is φ = 14062233225600.

The previous prime is 21211212011929. The next prime is 21211212012043. The reversal of 21211212012021 is 12021021211212.

It can be written as a sum of positive squares in 4 ways, for example, as 169817343921 + 21041394668100 = 412089^2 + 4587090^2 .

It is not a de Polignac number, because 21211212012021 - 2⁷ = 21211212011893 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 21211212011985 and 21211212012003.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21211212012521) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 55424995 + ... + 55806383.

It is an arithmetic number, because the mean of its divisors is an integer number (1283694730045).

Almost surely, 2^{21211212012021} is an apocalyptic number.

It is an amenable number.

21211212012021 is a deficient number, since it is larger than the sum of its proper divisors (9597461509059).

21211212012021 is a wasteful number, since it uses less digits than its factorization.

21211212012021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 415717 (or 415714 counting only the distinct ones).

The product of its (nonzero) digits is 64, while the sum is 18.

Adding to 21211212012021 its reverse (12021021211212), we get a palindrome (33232233223233).

The spelling of 21211212012021 in words is "twenty-one trillion, two hundred eleven billion, two hundred twelve million, twelve thousand, twenty-one".