21210210110021 has 4 divisors (see below), whose sum is σ = 21298219280844. Its totient is φ = 21122200939200.

The previous prime is 21210210109981. The next prime is 21210210110053. The reversal of 21210210110021 is 12001101201212.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 17738509547521 + 3471700562500 = 4211711^2 + 1863250^2 .

It is a cyclic number.

It is not a de Polignac number, because 21210210110021 - 2³⁸ = 20935332203077 is a prime.

It is a super-2 number, since 2×21210210110021² (a number of 27 digits) contains 22 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a junction number, because it is equal to n+sod(n) for n = 21210210109978 and 21210210110005.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21210210110071) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 44004585050 + ... + 44004585531.

It is an arithmetic number, because the mean of its divisors is an integer number (5324554820211).

Almost surely, 2^{21210210110021} is an apocalyptic number.

It is an amenable number.

21210210110021 is a deficient number, since it is larger than the sum of its proper divisors (88009170823).

21210210110021 is an equidigital number, since it uses as much as digits as its factorization.

21210210110021 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 88009170822.

The product of its (nonzero) digits is 16, while the sum is 14.

Adding to 21210210110021 its reverse (12001101201212), we get a palindrome (33211311311233).

The spelling of 21210210110021 in words is "twenty-one trillion, two hundred ten billion, two hundred ten million, one hundred ten thousand, twenty-one".