420213821 has 2 divisors, whose sum is σ = 420213822. Its totient is φ = 420213820.

The previous prime is 420213817. The next prime is 420213853. The reversal of 420213821 is 128312024.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 406627225 + 13586596 = 20165^2 + 3686^2 .

It is a cyclic number.

It is not a de Polignac number, because 420213821 - 2² = 420213817 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (420213881) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 210106910 + 210106911.

It is an arithmetic number, because the mean of its divisors is an integer number (210106911).

Almost surely, 2^420213821 is an apocalyptic number.

It is an amenable number.

420213821 is a deficient number, since it is larger than the sum of its proper divisors (1).

420213821 is an equidigital number, since it uses as much as digits as its factorization.

420213821 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 768, while the sum is 23.

The square root of 420213821 is about 20499.1175663734. The cubic root of 420213821 is about 749.0143027317.

Adding to 420213821 its reverse (128312024), we get a palindrome (548525845).

The spelling of 420213821 in words is "four hundred twenty million, two hundred thirteen thousand, eight hundred twenty-one".