81738169 has 2 divisors, whose sum is σ = 81738170. Its totient is φ = 81738168.

The previous prime is 81738161. The next prime is 81738179. The reversal of 81738169 is 96183718.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 45738169 + 36000000 = 6763^2 + 6000^2 .

It is a cyclic number.

It is not a de Polignac number, because 81738169 - 2³ = 81738161 is a prime.

It is a super-2 number, since 2×81738169² = 13362256542945122, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (81738161) 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, 40869084 + 40869085.

It is an arithmetic number, because the mean of its divisors is an integer number (40869085).

Almost surely, 2^81738169 is an apocalyptic number.

It is an amenable number.

81738169 is a deficient number, since it is larger than the sum of its proper divisors (1).

81738169 is an equidigital number, since it uses as much as digits as its factorization.

81738169 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 72576, while the sum is 43.

The square root of 81738169 is about 9040.9163805446. The cubic root of 81738169 is about 433.9852490615.

The spelling of 81738169 in words is "eighty-one million, seven hundred thirty-eight thousand, one hundred sixty-nine".