21778205404589 has 2 divisors, whose sum is σ = 21778205404590. Its totient is φ = 21778205404588.

The previous prime is 21778205404451. The next prime is 21778205404649. The reversal of 21778205404589 is 98540450287712.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 12594456983689 + 9183748420900 = 3548867^2 + 3030470^2 .

It is a cyclic number.

It is not a de Polignac number, because 21778205404589 - 2¹⁶ = 21778205339053 is a prime.

It is a Sophie Germain prime.

It is a Curzon number.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21778205406589) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10889102702294 + 10889102702295.

It is an arithmetic number, because the mean of its divisors is an integer number (10889102702295).

Almost surely, 2^{21778205404589} is an apocalyptic number.

It is an amenable number.

21778205404589 is a deficient number, since it is larger than the sum of its proper divisors (1).

21778205404589 is an equidigital number, since it uses as much as digits as its factorization.

21778205404589 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 45158400, while the sum is 62.

The spelling of 21778205404589 in words is "twenty-one trillion, seven hundred seventy-eight billion, two hundred five million, four hundred four thousand, five hundred eighty-nine".