20434430021 has 2 divisors, whose sum is σ = 20434430022. Its totient is φ = 20434430020.

The previous prime is 20434430011. The next prime is 20434430101. The reversal of 20434430021 is 12003443402.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17765157796 + 2669272225 = 133286^2 + 51665^2 .

It is a cyclic number.

It is not a de Polignac number, because 20434430021 - 2¹⁸ = 20434167877 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20434430011) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10217215010 + 10217215011.

It is an arithmetic number, because the mean of its divisors is an integer number (10217215011).

Almost surely, 2^20434430021 is an apocalyptic number.

It is an amenable number.

20434430021 is a deficient number, since it is larger than the sum of its proper divisors (1).

20434430021 is an equidigital number, since it uses as much as digits as its factorization.

20434430021 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2304, while the sum is 23.

Adding to 20434430021 its reverse (12003443402), we get a palindrome (32437873423).

The spelling of 20434430021 in words is "twenty billion, four hundred thirty-four million, four hundred thirty thousand, twenty-one".