821209084769 has 2 divisors, whose sum is σ = 821209084770. Its totient is φ = 821209084768.

The previous prime is 821209084697. The next prime is 821209084807. The reversal of 821209084769 is 967480902128.

Together with previous prime (821209084697) it forms an Ormiston pair, because they use the same digits, order apart.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 557244334144 + 263964750625 = 746488^2 + 513775^2 .

It is a cyclic number.

It is not a de Polignac number, because 821209084769 - 2¹² = 821209080673 is a prime.

It is a super-2 number, since 2×821209084769² (a number of 25 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (821209054769) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 410604542384 + 410604542385.

It is an arithmetic number, because the mean of its divisors is an integer number (410604542385).

Almost surely, 2^821209084769 is an apocalyptic number.

It is an amenable number.

821209084769 is a deficient number, since it is larger than the sum of its proper divisors (1).

821209084769 is an equidigital number, since it uses as much as digits as its factorization.

821209084769 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 3483648, while the sum is 56.

The spelling of 821209084769 in words is "eight hundred twenty-one billion, two hundred nine million, eighty-four thousand, seven hundred sixty-nine".