21201022081 has 2 divisors, whose sum is σ = 21201022082. Its totient is φ = 21201022080.

The previous prime is 21201022057. The next prime is 21201022123. The reversal of 21201022081 is 18022010212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20769421456 + 431600625 = 144116^2 + 20775^2 .

It is a cyclic number.

It is not a de Polignac number, because 21201022081 - 2¹⁷ = 21200891009 is a prime.

It is a super-2 number, since 2×21201022081² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21201022981) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10600511040 + 10600511041.

It is an arithmetic number, because the mean of its divisors is an integer number (10600511041).

Almost surely, 2^21201022081 is an apocalyptic number.

It is an amenable number.

21201022081 is a deficient number, since it is larger than the sum of its proper divisors (1).

21201022081 is an equidigital number, since it uses as much as digits as its factorization.

21201022081 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.

Adding to 21201022081 its reverse (18022010212), we get a palindrome (39223032293).

It can be divided in two parts, 2120 and 1022081, that added together give a palindrome (1024201).

The spelling of 21201022081 in words is "twenty-one billion, two hundred one million, twenty-two thousand, eighty-one".