21211001201081 has 2 divisors, whose sum is σ = 21211001201082. Its totient is φ = 21211001201080.

The previous prime is 21211001201009. The next prime is 21211001201101. The reversal of 21211001201081 is 18010210011212.

It is a happy number.

It is an a-pointer prime, because the next prime (21211001201101) can be obtained adding 21211001201081 to its sum of digits (20).

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 15252110106025 + 5958891095056 = 3905395^2 + 2441084^2 .

It is a cyclic number.

It is not a de Polignac number, because 21211001201081 - 2¹⁰ = 21211001200057 is a prime.

It is a super-2 number, since 2×21211001201081² (a number of 27 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21211001209081) 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, 10605500600540 + 10605500600541.

It is an arithmetic number, because the mean of its divisors is an integer number (10605500600541).

Almost surely, 2^{21211001201081} is an apocalyptic number.

It is an amenable number.

21211001201081 is a deficient number, since it is larger than the sum of its proper divisors (1).

21211001201081 is an equidigital number, since it uses as much as digits as its factorization.

21211001201081 is an odious number, because the sum of its binary digits is odd.

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

Adding to 21211001201081 its reverse (18010210011212), we get a palindrome (39221211212293).

The spelling of 21211001201081 in words is "twenty-one trillion, two hundred eleven billion, one million, two hundred one thousand, eighty-one".