221021020081 has 2 divisors, whose sum is σ = 221021020082. Its totient is φ = 221021020080.

The previous prime is 221021020079. The next prime is 221021020117. The reversal of 221021020081 is 180020120122.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 184848403600 + 36172616481 = 429940^2 + 190191^2 .

It is a cyclic number.

It is not a de Polignac number, because 221021020081 - 2¹ = 221021020079 is a prime.

It is a super-2 number, since 2×221021020081² (a number of 23 digits) contains 22 as substring.

Together with 221021020079, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (221021020001) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 110510510040 + 110510510041.

It is an arithmetic number, because the mean of its divisors is an integer number (110510510041).

Almost surely, 2^221021020081 is an apocalyptic number.

It is an amenable number.

221021020081 is a deficient number, since it is larger than the sum of its proper divisors (1).

221021020081 is an equidigital number, since it uses as much as digits as its factorization.

221021020081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 128, while the sum is 19.

The spelling of 221021020081 in words is "two hundred twenty-one billion, twenty-one million, twenty thousand, eighty-one".