21211010020181 has 2 divisors, whose sum is σ = 21211010020182. Its totient is φ = 21211010020180.

The previous prime is 21211010020163. The next prime is 21211010020229. The reversal of 21211010020181 is 18102001011212.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13850559629956 + 7360450390225 = 3721634^2 + 2713015^2 .

It is a cyclic number.

It is not a de Polignac number, because 21211010020181 - 2¹⁴ = 21211010003797 is a prime.

It is a super-2 number, since 2×21211010020181² (a number of 27 digits) contains 22 as substring.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21211010020381) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10605505010090 + 10605505010091.

It is an arithmetic number, because the mean of its divisors is an integer number (10605505010091).

Almost surely, 2^{21211010020181} is an apocalyptic number.

It is an amenable number.

21211010020181 is a deficient number, since it is larger than the sum of its proper divisors (1).

21211010020181 is an equidigital number, since it uses as much as digits as its factorization.

21211010020181 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 64, while the sum is 20.

Adding to 21211010020181 its reverse (18102001011212), we get a palindrome (39313011031393).

The spelling of 21211010020181 in words is "twenty-one trillion, two hundred eleven billion, ten million, twenty thousand, one hundred eighty-one".