21200021210161 has 2 divisors, whose sum is σ = 21200021210162. Its totient is φ = 21200021210160.

The previous prime is 21200021210113. The next prime is 21200021210227. The reversal of 21200021210161 is 16101212000212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18648794480625 + 2551226729536 = 4318425^2 + 1597256^2 .

It is a cyclic number.

It is not a de Polignac number, because 21200021210161 - 2⁹ = 21200021209649 is a prime.

It is a super-2 number, since 2×21200021210161² (a number of 27 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21200021210461) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10600010605080 + 10600010605081.

It is an arithmetic number, because the mean of its divisors is an integer number (10600010605081).

Almost surely, 2^{21200021210161} is an apocalyptic number.

It is an amenable number.

21200021210161 is a deficient number, since it is larger than the sum of its proper divisors (1).

21200021210161 is an equidigital number, since it uses as much as digits as its factorization.

21200021210161 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 96, while the sum is 19.

Adding to 21200021210161 its reverse (16101212000212), we get a palindrome (37301233210373).

The spelling of 21200021210161 in words is "twenty-one trillion, two hundred billion, twenty-one million, two hundred ten thousand, one hundred sixty-one".