21012102122173 has 2 divisors, whose sum is σ = 21012102122174. Its totient is φ = 21012102122172.

The previous prime is 21012102122149. The next prime is 21012102122279. The reversal of 21012102122173 is 37122120121012.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 15607769744889 + 5404332377284 = 3950667^2 + 2324722^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21012102122173 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21012102125173) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10506051061086 + 10506051061087.

It is an arithmetic number, because the mean of its divisors is an integer number (10506051061087).

Almost surely, 2^{21012102122173} is an apocalyptic number.

It is an amenable number.

21012102122173 is a deficient number, since it is larger than the sum of its proper divisors (1).

21012102122173 is an equidigital number, since it uses as much as digits as its factorization.

21012102122173 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 672, while the sum is 25.

Adding to 21012102122173 its reverse (37122120121012), we get a palindrome (58134222243185).

The spelling of 21012102122173 in words is "twenty-one trillion, twelve billion, one hundred two million, one hundred twenty-two thousand, one hundred seventy-three".