21020021202181 has 2 divisors, whose sum is σ = 21020021202182. Its totient is φ = 21020021202180.

The previous prime is 21020021202151. The next prime is 21020021202223. The reversal of 21020021202181 is 18120212002012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18189329361025 + 2830691841156 = 4264895^2 + 1682466^2 .

It is a cyclic number.

It is not a de Polignac number, because 21020021202181 - 2¹³ = 21020021193989 is a prime.

It is a super-2 number, since 2×21020021202181² (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 (21020021202121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10510010601090 + 10510010601091.

It is an arithmetic number, because the mean of its divisors is an integer number (10510010601091).

Almost surely, 2^{21020021202181} is an apocalyptic number.

It is an amenable number.

21020021202181 is a deficient number, since it is larger than the sum of its proper divisors (1).

21020021202181 is an equidigital number, since it uses as much as digits as its factorization.

21020021202181 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 256, while the sum is 22.

Adding to 21020021202181 its reverse (18120212002012), we get a palindrome (39140233204193).

The spelling of 21020021202181 in words is "twenty-one trillion, twenty billion, twenty-one million, two hundred two thousand, one hundred eighty-one".