21067552081 has 2 divisors, whose sum is σ = 21067552082. Its totient is φ = 21067552080.

The previous prime is 21067552069. The next prime is 21067552109. The reversal of 21067552081 is 18025576012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 13465281600 + 7602270481 = 116040^2 + 87191^2 .

It is a cyclic number.

It is not a de Polignac number, because 21067552081 - 2²³ = 21059163473 is a prime.

It is a super-2 number, since 2×21067552081² (a number of 21 digits) contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 21067552081.

It is not a weakly prime, because it can be changed into another prime (21067552021) 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, 10533776040 + 10533776041.

It is an arithmetic number, because the mean of its divisors is an integer number (10533776041).

Almost surely, 2^21067552081 is an apocalyptic number.

It is an amenable number.

21067552081 is a deficient number, since it is larger than the sum of its proper divisors (1).

21067552081 is an equidigital number, since it uses as much as digits as its factorization.

21067552081 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 33600, while the sum is 37.

The spelling of 21067552081 in words is "twenty-one billion, sixty-seven million, five hundred fifty-two thousand, eighty-one".