856332821 has 2 divisors, whose sum is σ = 856332822. Its totient is φ = 856332820.

The previous prime is 856332817. The next prime is 856332887. The reversal of 856332821 is 128233658.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 571735921 + 284596900 = 23911^2 + 16870^2 .

It is a cyclic number.

It is not a de Polignac number, because 856332821 - 2² = 856332817 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (856332811) 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, 428166410 + 428166411.

It is an arithmetic number, because the mean of its divisors is an integer number (428166411).

Almost surely, 2^856332821 is an apocalyptic number.

It is an amenable number.

856332821 is a deficient number, since it is larger than the sum of its proper divisors (1).

856332821 is an equidigital number, since it uses as much as digits as its factorization.

856332821 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 69120, while the sum is 38.

The square root of 856332821 is about 29263.1649176913. The cubic root of 856332821 is about 949.6149209390.

The spelling of 856332821 in words is "eight hundred fifty-six million, three hundred thirty-two thousand, eight hundred twenty-one".