81079891769 has 2 divisors, whose sum is σ = 81079891770. Its totient is φ = 81079891768.

The previous prime is 81079891759. The next prime is 81079891793. The reversal of 81079891769 is 96719897018.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 69820135225 + 11259756544 = 264235^2 + 106112^2 .

It is a cyclic number.

It is not a de Polignac number, because 81079891769 - 2¹² = 81079887673 is a prime.

It is a super-2 number, since 2×81079891769² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (81079891759) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40539945884 + 40539945885.

It is an arithmetic number, because the mean of its divisors is an integer number (40539945885).

Almost surely, 2^81079891769 is an apocalyptic number.

It is an amenable number.

81079891769 is a deficient number, since it is larger than the sum of its proper divisors (1).

81079891769 is an equidigital number, since it uses as much as digits as its factorization.

81079891769 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 13716864, while the sum is 65.

The spelling of 81079891769 in words is "eighty-one billion, seventy-nine million, eight hundred ninety-one thousand, seven hundred sixty-nine".