21214420421 has 2 divisors, whose sum is σ = 21214420422. Its totient is φ = 21214420420.

The previous prime is 21214420327. The next prime is 21214420457. The reversal of 21214420421 is 12402441212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 11043697921 + 10170722500 = 105089^2 + 100850^2 .

It is a cyclic number.

It is not a de Polignac number, because 21214420421 - 2¹⁴ = 21214404037 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21214420321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10607210210 + 10607210211.

It is an arithmetic number, because the mean of its divisors is an integer number (10607210211).

Almost surely, 2^21214420421 is an apocalyptic number.

It is an amenable number.

21214420421 is a deficient number, since it is larger than the sum of its proper divisors (1).

21214420421 is an equidigital number, since it uses as much as digits as its factorization.

21214420421 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1024, while the sum is 23.

Adding to 21214420421 its reverse (12402441212), we get a palindrome (33616861633).

The spelling of 21214420421 in words is "twenty-one billion, two hundred fourteen million, four hundred twenty thousand, four hundred twenty-one".