821648129 has 2 divisors, whose sum is σ = 821648130. Its totient is φ = 821648128.

The previous prime is 821648117. The next prime is 821648143. The reversal of 821648129 is 921846128.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 661878529 + 159769600 = 25727^2 + 12640^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-821648129 is a prime.

It is not a weakly prime, because it can be changed into another prime (821648929) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410824064 + 410824065.

It is an arithmetic number, because the mean of its divisors is an integer number (410824065).

Almost surely, 2^821648129 is an apocalyptic number.

It is an amenable number.

821648129 is a deficient number, since it is larger than the sum of its proper divisors (1).

821648129 is an equidigital number, since it uses as much as digits as its factorization.

821648129 is an evil number, because the sum of its binary digits is even.

The product of its digits is 55296, while the sum is 41.

The square root of 821648129 is about 28664.4052615783. The cubic root of 821648129 is about 936.6168290472.

The spelling of 821648129 in words is "eight hundred twenty-one million, six hundred forty-eight thousand, one hundred twenty-nine".