21782844169 has 2 divisors, whose sum is σ = 21782844170. Its totient is φ = 21782844168.

The previous prime is 21782844137. The next prime is 21782844179. The reversal of 21782844169 is 96144828712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 21781922569 + 921600 = 147587^2 + 960^2 .

It is a cyclic number.

It is not a de Polignac number, because 21782844169 - 2⁵ = 21782844137 is a prime.

It is a super-2 number, since 2×21782844169² (a number of 21 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (21782844179) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10891422084 + 10891422085.

It is an arithmetic number, because the mean of its divisors is an integer number (10891422085).

Almost surely, 2^21782844169 is an apocalyptic number.

It is an amenable number.

21782844169 is a deficient number, since it is larger than the sum of its proper divisors (1).

21782844169 is an equidigital number, since it uses as much as digits as its factorization.

21782844169 is an evil number, because the sum of its binary digits is even.

The product of its digits is 1548288, while the sum is 52.

The spelling of 21782844169 in words is "twenty-one billion, seven hundred eighty-two million, eight hundred forty-four thousand, one hundred sixty-nine".