820421447 has 2 divisors, whose sum is σ = 820421448. Its totient is φ = 820421446.

The previous prime is 820421443. The next prime is 820421509. The reversal of 820421447 is 744124028.

820421447 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a weak prime.

It is a cyclic number.

It is not a de Polignac number, because 820421447 - 2² = 820421443 is a prime.

It is a Chen prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (820421443) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410210723 + 410210724.

It is an arithmetic number, because the mean of its divisors is an integer number (410210724).

Almost surely, 2^820421447 is an apocalyptic number.

820421447 is a deficient number, since it is larger than the sum of its proper divisors (1).

820421447 is an equidigital number, since it uses as much as digits as its factorization.

820421447 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 14336, while the sum is 32.

The square root of 820421447 is about 28642.9999650875. Note that the first 4 decimals coincide. The cubic root of 820421447 is about 936.1504886087.

The spelling of 820421447 in words is "eight hundred twenty million, four hundred twenty-one thousand, four hundred forty-seven".