21121221010021 has 4 divisors (see below), whose sum is σ = 23041332010944. Its totient is φ = 19201110009100.

The previous prime is 21121221009949. The next prime is 21121221010111. The reversal of 21121221010021 is 12001012212112.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21121221010021 - 2¹⁵ = 21121220977253 is a prime.

It is a super-2 number, since 2×21121221010021² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21121221009977 and 21121221010004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121221010921) 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, 960055500445 + ... + 960055500466.

It is an arithmetic number, because the mean of its divisors is an integer number (5760333002736).

Almost surely, 2^{21121221010021} is an apocalyptic number.

It is an amenable number.

21121221010021 is a deficient number, since it is larger than the sum of its proper divisors (1920111000923).

21121221010021 is a wasteful number, since it uses less digits than its factorization.

21121221010021 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1920111000922.

The product of its (nonzero) digits is 32, while the sum is 16.

Adding to 21121221010021 its reverse (12001012212112), we get a palindrome (33122233222133).

The spelling of 21121221010021 in words is "twenty-one trillion, one hundred twenty-one billion, two hundred twenty-one million, ten thousand, twenty-one".