21175433378681 has 2 divisors, whose sum is σ = 21175433378682. Its totient is φ = 21175433378680.

The previous prime is 21175433378633. The next prime is 21175433378707. The reversal of 21175433378681 is 18687333457112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16114805205625 + 5060628173056 = 4014325^2 + 2249584^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21175433378681 is a prime.

It is a super-2 number, since 2×21175433378681² (a number of 27 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 21175433378681.

It is not a weakly prime, because it can be changed into another prime (21175433378881) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10587716689340 + 10587716689341.

It is an arithmetic number, because the mean of its divisors is an integer number (10587716689341).

Almost surely, 2^{21175433378681} is an apocalyptic number.

It is an amenable number.

21175433378681 is a deficient number, since it is larger than the sum of its proper divisors (1).

21175433378681 is an equidigital number, since it uses as much as digits as its factorization.

21175433378681 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 20321280, while the sum is 59.

The spelling of 21175433378681 in words is "twenty-one trillion, one hundred seventy-five billion, four hundred thirty-three million, three hundred seventy-eight thousand, six hundred eighty-one".