21271402129 has 2 divisors, whose sum is σ = 21271402130. Its totient is φ = 21271402128.

The previous prime is 21271402127. The next prime is 21271402169. The reversal of 21271402129 is 92120417212.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 18029238529 + 3242163600 = 134273^2 + 56940^2 .

It is a cyclic number.

It is not a de Polignac number, because 21271402129 - 2¹ = 21271402127 is a prime.

Together with 21271402127, it forms a pair of twin primes.

It is a self number, because there is not a number n which added to its sum of digits gives 21271402129.

It is not a weakly prime, because it can be changed into another prime (21271402121) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10635701064 + 10635701065.

It is an arithmetic number, because the mean of its divisors is an integer number (10635701065).

Almost surely, 2^21271402129 is an apocalyptic number.

It is an amenable number.

21271402129 is a deficient number, since it is larger than the sum of its proper divisors (1).

21271402129 is an equidigital number, since it uses as much as digits as its factorization.

21271402129 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 4032, while the sum is 31.

The spelling of 21271402129 in words is "twenty-one billion, two hundred seventy-one million, four hundred two thousand, one hundred twenty-nine".