20421408173 has 2 divisors, whose sum is σ = 20421408174. Its totient is φ = 20421408172.

The previous prime is 20421408149. The next prime is 20421408223. The reversal of 20421408173 is 37180412402.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 17168074729 + 3253333444 = 131027^2 + 57038^2 .

It is a cyclic number.

It is not a de Polignac number, because 20421408173 - 2⁶ = 20421408109 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (20421408143) 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, 10210704086 + 10210704087.

It is an arithmetic number, because the mean of its divisors is an integer number (10210704087).

Almost surely, 2^20421408173 is an apocalyptic number.

It is an amenable number.

20421408173 is a deficient number, since it is larger than the sum of its proper divisors (1).

20421408173 is an equidigital number, since it uses as much as digits as its factorization.

20421408173 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 10752, while the sum is 32.

The spelling of 20421408173 in words is "twenty billion, four hundred twenty-one million, four hundred eight thousand, one hundred seventy-three".