21165559573 has 2 divisors, whose sum is σ = 21165559574. Its totient is φ = 21165559572.

The previous prime is 21165559543. The next prime is 21165559577. The reversal of 21165559573 is 37595556112.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20266939044 + 898620529 = 142362^2 + 29977^2 .

It is a cyclic number.

It is not a de Polignac number, because 21165559573 - 2⁹ = 21165559061 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21165559577) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10582779786 + 10582779787.

It is an arithmetic number, because the mean of its divisors is an integer number (10582779787).

Almost surely, 2^21165559573 is an apocalyptic number.

It is an amenable number.

21165559573 is a deficient number, since it is larger than the sum of its proper divisors (1).

21165559573 is an equidigital number, since it uses as much as digits as its factorization.

21165559573 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1417500, while the sum is 49.

The spelling of 21165559573 in words is "twenty-one billion, one hundred sixty-five million, five hundred fifty-nine thousand, five hundred seventy-three".