21787028773 has 2 divisors, whose sum is σ = 21787028774. Its totient is φ = 21787028772.

The previous prime is 21787028717. The next prime is 21787028789. The reversal of 21787028773 is 37782078712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20472458724 + 1314570049 = 143082^2 + 36257^2 .

It is a cyclic number.

It is not a de Polignac number, because 21787028773 - 2⁹ = 21787028261 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21787028773.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21787028173) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10893514386 + 10893514387.

It is an arithmetic number, because the mean of its divisors is an integer number (10893514387).

Almost surely, 2^21787028773 is an apocalyptic number.

It is an amenable number.

21787028773 is a deficient number, since it is larger than the sum of its proper divisors (1).

21787028773 is an equidigital number, since it uses as much as digits as its factorization.

21787028773 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1843968, while the sum is 52.

The spelling of 21787028773 in words is "twenty-one billion, seven hundred eighty-seven million, twenty-eight thousand, seven hundred seventy-three".