21030321173 has 2 divisors, whose sum is σ = 21030321174. Its totient is φ = 21030321172.

The previous prime is 21030321161. The next prime is 21030321199. The reversal of 21030321173 is 37112303012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 12242758609 + 8787562564 = 110647^2 + 93742^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21030321173 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21030321113) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10515160586 + 10515160587.

It is an arithmetic number, because the mean of its divisors is an integer number (10515160587).

Almost surely, 2^21030321173 is an apocalyptic number.

It is an amenable number.

21030321173 is a deficient number, since it is larger than the sum of its proper divisors (1).

21030321173 is an equidigital number, since it uses as much as digits as its factorization.

21030321173 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 756, while the sum is 23.

Adding to 21030321173 its reverse (37112303012), we get a palindrome (58142624185).

The spelling of 21030321173 in words is "twenty-one billion, thirty million, three hundred twenty-one thousand, one hundred seventy-three".