21012101000081 has 2 divisors, whose sum is σ = 21012101000082. Its totient is φ = 21012101000080.

The previous prime is 21012100999993. The next prime is 21012101000087. The reversal of 21012101000081 is 18000010121012.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 19781368140625 + 1230732859456 = 4447625^2 + 1109384^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21012101000081 is a prime.

It is a super-2 number, since 2×21012101000081² (a number of 27 digits) contains 22 as substring.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (21012101000087) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10506050500040 + 10506050500041.

It is an arithmetic number, because the mean of its divisors is an integer number (10506050500041).

Almost surely, 2^{21012101000081} is an apocalyptic number.

It is an amenable number.

21012101000081 is a deficient number, since it is larger than the sum of its proper divisors (1).

21012101000081 is an equidigital number, since it uses as much as digits as its factorization.

21012101000081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 32, while the sum is 17.

Adding to 21012101000081 its reverse (18000010121012), we get a palindrome (39012111121093).

The spelling of 21012101000081 in words is "twenty-one trillion, twelve billion, one hundred one million, eighty-one", and thus it is an aban number.