21121210210021 has 8 divisors (see below), whose sum is σ = 21850261093080. Its totient is φ = 20392208212992.

The previous prime is 21121210209991. The next prime is 21121210210033. The reversal of 21121210210021 is 12001201212112.

It can be written as a sum of positive squares in 4 ways, for example, as 328431001921 + 20792779208100 = 573089^2 + 4559910^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 21121210210021 - 2³¹ = 21119062726373 is a prime.

It is a super-2 number, since 2×21121210210021² (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 = 21121210209977 and 21121210210004.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21121210210921) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 11341420 + ... + 13071733.

It is an arithmetic number, because the mean of its divisors is an integer number (2731282636635).

Almost surely, 2^{21121210210021} is an apocalyptic number.

It is an amenable number.

21121210210021 is a deficient number, since it is larger than the sum of its proper divisors (729050883059).

21121210210021 is a wasteful number, since it uses less digits than its factorization.

21121210210021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24443015.

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

Adding to 21121210210021 its reverse (12001201212112), we get a palindrome (33122411422133).

The spelling of 21121210210021 in words is "twenty-one trillion, one hundred twenty-one billion, two hundred ten million, two hundred ten thousand, twenty-one".