820857047 has 2 divisors, whose sum is σ = 820857048. Its totient is φ = 820857046.

The previous prime is 820857017. The next prime is 820857049. The reversal of 820857047 is 740758028.

It is a strong prime.

It is a cyclic number.

It is not a de Polignac number, because 820857047 - 2⁶ = 820856983 is a prime.

Together with 820857049, it forms a pair of twin primes.

It is a Chen prime.

It is a junction number, because it is equal to n+sod(n) for n = 820856995 and 820857013.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (820857049) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410428523 + 410428524.

It is an arithmetic number, because the mean of its divisors is an integer number (410428524).

Almost surely, 2^820857047 is an apocalyptic number.

820857047 is a deficient number, since it is larger than the sum of its proper divisors (1).

820857047 is an equidigital number, since it uses as much as digits as its factorization.

820857047 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 125440, while the sum is 41.

The square root of 820857047 is about 28650.6029081414. The cubic root of 820857047 is about 936.3161412760.

The spelling of 820857047 in words is "eight hundred twenty million, eight hundred fifty-seven thousand, forty-seven".