21331302173 has 2 divisors, whose sum is σ = 21331302174. Its totient is φ = 21331302172.

The previous prime is 21331302169. The next prime is 21331302191. The reversal of 21331302173 is 37120313312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 20885163289 + 446138884 = 144517^2 + 21122^2 .

It is a cyclic number.

It is not a de Polignac number, because 21331302173 - 2² = 21331302169 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21331302193) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10665651086 + 10665651087.

It is an arithmetic number, because the mean of its divisors is an integer number (10665651087).

Almost surely, 2^21331302173 is an apocalyptic number.

It is an amenable number.

21331302173 is a deficient number, since it is larger than the sum of its proper divisors (1).

21331302173 is an equidigital number, since it uses as much as digits as its factorization.

21331302173 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 2268, while the sum is 26.

Adding to 21331302173 its reverse (37120313312), we get a palindrome (58451615485).

The spelling of 21331302173 in words is "twenty-one billion, three hundred thirty-one million, three hundred two thousand, one hundred seventy-three".