820129 has 2 divisors, whose sum is σ = 820130. Its totient is φ = 820128.

The previous prime is 820117. The next prime is 820133. The reversal of 820129 is 921028.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 528529 + 291600 = 727^2 + 540^2 .

It is a cyclic number.

It is not a de Polignac number, because 820129 - 2⁹ = 819617 is a prime.

It is a super-2 number, since 2×820129² = 1345223153282, which contains 22 as substring.

It is a zygodrome in base 3.

It is not a weakly prime, because it can be changed into another prime (820109) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410064 + 410065.

It is an arithmetic number, because the mean of its divisors is an integer number (410065).

2⁸²⁰¹²⁹ is an apocalyptic number.

It is an amenable number.

820129 is a deficient number, since it is larger than the sum of its proper divisors (1).

820129 is an equidigital number, since it uses as much as digits as its factorization.

820129 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 22.

The square root of 820129 is about 905.6097393469. The cubic root of 820129 is about 93.6039242151.

It can be divided in two parts, 820 and 129, that added together give a palindrome (949).

The spelling of 820129 in words is "eight hundred twenty thousand, one hundred twenty-nine".