21165403271 has 2 divisors, whose sum is σ = 21165403272. Its totient is φ = 21165403270.

The previous prime is 21165403219. The next prime is 21165403277. The reversal of 21165403271 is 17230456112.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 21165403271 - 2²² = 21161208967 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21165403277) 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, 10582701635 + 10582701636.

It is an arithmetic number, because the mean of its divisors is an integer number (10582701636).

Almost surely, 2^21165403271 is an apocalyptic number.

21165403271 is a deficient number, since it is larger than the sum of its proper divisors (1).

21165403271 is an equidigital number, since it uses as much as digits as its factorization.

21165403271 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10080, while the sum is 32.

Adding to 21165403271 its reverse (17230456112), we get a palindrome (38395859383).

The spelling of 21165403271 in words is "twenty-one billion, one hundred sixty-five million, four hundred three thousand, two hundred seventy-one".