21088805081 has 2 divisors, whose sum is σ = 21088805082. Its totient is φ = 21088805080.

The previous prime is 21088805077. The next prime is 21088805119. The reversal of 21088805081 is 18050888012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20033854681 + 1054950400 = 141541^2 + 32480^2 .

It is a cyclic number.

It is not a de Polignac number, because 21088805081 - 2² = 21088805077 is a prime.

It is a super-2 number, since 2×21088805081² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21088805681) 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, 10544402540 + 10544402541.

It is an arithmetic number, because the mean of its divisors is an integer number (10544402541).

Almost surely, 2^21088805081 is an apocalyptic number.

It is an amenable number.

21088805081 is a deficient number, since it is larger than the sum of its proper divisors (1).

21088805081 is an equidigital number, since it uses as much as digits as its factorization.

21088805081 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 40960, while the sum is 41.

The spelling of 21088805081 in words is "twenty-one billion, eighty-eight million, eight hundred five thousand, eighty-one".