821000129 has 2 divisors, whose sum is σ = 821000130. Its totient is φ = 821000128.

The previous prime is 821000119. The next prime is 821000177. The reversal of 821000129 is 921000128.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 721459600 + 99540529 = 26860^2 + 9977^2 .

It is a cyclic number.

It is not a de Polignac number, because 821000129 - 2⁸ = 820999873 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (821000119) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410500064 + 410500065.

It is an arithmetic number, because the mean of its divisors is an integer number (410500065).

Almost surely, 2^821000129 is an apocalyptic number.

It is an amenable number.

821000129 is a deficient number, since it is larger than the sum of its proper divisors (1).

821000129 is an equidigital number, since it uses as much as digits as its factorization.

821000129 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 288, while the sum is 23.

The square root of 821000129 is about 28653.0998148542. The cubic root of 821000129 is about 936.3705405990.

Subtracting 821000129 from its reverse (921000128), we obtain a palindrome (99999999).

The spelling of 821000129 in words is "eight hundred twenty-one million, one hundred twenty-nine", and thus it is an aban number.