21780766193 has 2 divisors, whose sum is σ = 21780766194. Its totient is φ = 21780766192.

The previous prime is 21780766181. The next prime is 21780766199. The reversal of 21780766193 is 39166708712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 13519410529 + 8261355664 = 116273^2 + 90892^2 .

It is a cyclic number.

It is not a de Polignac number, because 21780766193 - 2¹⁰ = 21780765169 is a prime.

It is not a weakly prime, because it can be changed into another prime (21780766199) 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, 10890383096 + 10890383097.

It is an arithmetic number, because the mean of its divisors is an integer number (10890383097).

Almost surely, 2^21780766193 is an apocalyptic number.

It is an amenable number.

21780766193 is a deficient number, since it is larger than the sum of its proper divisors (1).

21780766193 is an equidigital number, since it uses as much as digits as its factorization.

21780766193 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 762048, while the sum is 50.

The spelling of 21780766193 in words is "twenty-one billion, seven hundred eighty million, seven hundred sixty-six thousand, one hundred ninety-three".