820643429 has 2 divisors, whose sum is σ = 820643430. Its totient is φ = 820643428.

The previous prime is 820643357. The next prime is 820643471. The reversal of 820643429 is 924346028.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 649740100 + 170903329 = 25490^2 + 13073^2 .

It is a cyclic number.

It is not a de Polignac number, because 820643429 - 2²⁸ = 552207973 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 820643392 and 820643401.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (820643729) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410321714 + 410321715.

It is an arithmetic number, because the mean of its divisors is an integer number (410321715).

Almost surely, 2^820643429 is an apocalyptic number.

It is an amenable number.

820643429 is a deficient number, since it is larger than the sum of its proper divisors (1).

820643429 is an equidigital number, since it uses as much as digits as its factorization.

820643429 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 82944, while the sum is 38.

The square root of 820643429 is about 28646.8746811934. The cubic root of 820643429 is about 936.2349126239.

The spelling of 820643429 in words is "eight hundred twenty million, six hundred forty-three thousand, four hundred twenty-nine".