420566821 has 2 divisors, whose sum is σ = 420566822. Its totient is φ = 420566820.

The previous prime is 420566803. The next prime is 420566831. The reversal of 420566821 is 128665024.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 260822500 + 159744321 = 16150^2 + 12639^2 .

It is a cyclic number.

It is not a de Polignac number, because 420566821 - 2¹¹ = 420564773 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (420566831) 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, 210283410 + 210283411.

It is an arithmetic number, because the mean of its divisors is an integer number (210283411).

Almost surely, 2^420566821 is an apocalyptic number.

It is an amenable number.

420566821 is a deficient number, since it is larger than the sum of its proper divisors (1).

420566821 is an equidigital number, since it uses as much as digits as its factorization.

420566821 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 23040, while the sum is 34.

The square root of 420566821 is about 20507.7258856266. The cubic root of 420566821 is about 749.2239801493.

The spelling of 420566821 in words is "four hundred twenty million, five hundred sixty-six thousand, eight hundred twenty-one".