21571266173 has 2 divisors, whose sum is σ = 21571266174. Its totient is φ = 21571266172.

The previous prime is 21571266137. The next prime is 21571266209. The reversal of 21571266173 is 37166217512.

Together with previous prime (21571266137) it forms an Ormiston pair, because they use the same digits, order apart.

It is a balanced prime because it is at equal distance from previous prime (21571266137) and next prime (21571266209).

It can be written as a sum of positive squares in only one way, i.e., 19299599929 + 2271666244 = 138923^2 + 47662^2 .

It is a cyclic number.

It is not a de Polignac number, because 21571266173 - 2¹⁸ = 21571004029 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21571266173.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21571266133) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10785633086 + 10785633087.

It is an arithmetic number, because the mean of its divisors is an integer number (10785633087).

Almost surely, 2^21571266173 is an apocalyptic number.

It is an amenable number.

21571266173 is a deficient number, since it is larger than the sum of its proper divisors (1).

21571266173 is an equidigital number, since it uses as much as digits as its factorization.

21571266173 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 105840, while the sum is 41.

The spelling of 21571266173 in words is "twenty-one billion, five hundred seventy-one million, two hundred sixty-six thousand, one hundred seventy-three".