820625821 has 2 divisors, whose sum is σ = 820625822. Its totient is φ = 820625820.

The previous prime is 820625801. The next prime is 820625833. The reversal of 820625821 is 128526028.

820625821 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 819963225 + 662596 = 28635^2 + 814^2 .

It is a cyclic number.

It is not a de Polignac number, because 820625821 - 2²⁹ = 283754909 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (820625801) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410312910 + 410312911.

It is an arithmetic number, because the mean of its divisors is an integer number (410312911).

Almost surely, 2^820625821 is an apocalyptic number.

It is an amenable number.

820625821 is a deficient number, since it is larger than the sum of its proper divisors (1).

820625821 is an equidigital number, since it uses as much as digits as its factorization.

820625821 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 15360, while the sum is 34.

The square root of 820625821 is about 28646.5673510807. The cubic root of 820625821 is about 936.2282165195.

The spelling of 820625821 in words is "eight hundred twenty million, six hundred twenty-five thousand, eight hundred twenty-one".