20305421 has 2 divisors, whose sum is σ = 20305422. Its totient is φ = 20305420.

The previous prime is 20305409. The next prime is 20305427. The reversal of 20305421 is 12450302.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 14478025 + 5827396 = 3805^2 + 2414^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-20305421 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 20305421.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20305427) 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, 10152710 + 10152711.

It is an arithmetic number, because the mean of its divisors is an integer number (10152711).

Almost surely, 2^20305421 is an apocalyptic number.

It is an amenable number.

20305421 is a deficient number, since it is larger than the sum of its proper divisors (1).

20305421 is an equidigital number, since it uses as much as digits as its factorization.

20305421 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 240, while the sum is 17.

The square root of 20305421 is about 4506.1536813562. The cubic root of 20305421 is about 272.8165207944.

Adding to 20305421 its reverse (12450302), we get a palindrome (32755723).

The spelling of 20305421 in words is "twenty million, three hundred five thousand, four hundred twenty-one".