422721821 has 2 divisors, whose sum is σ = 422721822. Its totient is φ = 422721820.

The previous prime is 422721749. The next prime is 422721851. The reversal of 422721821 is 128127224.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 380796196 + 41925625 = 19514^2 + 6475^2 .

It is a cyclic number.

It is not a de Polignac number, because 422721821 - 2¹⁸ = 422459677 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (422721851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 211360910 + 211360911.

It is an arithmetic number, because the mean of its divisors is an integer number (211360911).

Almost surely, 2^422721821 is an apocalyptic number.

It is an amenable number.

422721821 is a deficient number, since it is larger than the sum of its proper divisors (1).

422721821 is an equidigital number, since it uses as much as digits as its factorization.

422721821 is an evil number, because the sum of its binary digits is even.

The product of its digits is 3584, while the sum is 29.

The square root of 422721821 is about 20560.1999260708. The cubic root of 422721821 is about 750.5014844616.

The spelling of 422721821 in words is "four hundred twenty-two million, seven hundred twenty-one thousand, eight hundred twenty-one".