81698180309 has 2 divisors, whose sum is σ = 81698180310. Its totient is φ = 81698180308.

The previous prime is 81698180273. The next prime is 81698180329. The reversal of 81698180309 is 90308189618.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 42326890225 + 39371290084 = 205735^2 + 198422^2 .

It is a cyclic number.

It is not a de Polignac number, because 81698180309 - 2¹² = 81698176213 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81698180329) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40849090154 + 40849090155.

It is an arithmetic number, because the mean of its divisors is an integer number (40849090155).

Almost surely, 2^81698180309 is an apocalyptic number.

It is an amenable number.

81698180309 is a deficient number, since it is larger than the sum of its proper divisors (1).

81698180309 is an equidigital number, since it uses as much as digits as its factorization.

81698180309 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 746496, while the sum is 53.

The spelling of 81698180309 in words is "eighty-one billion, six hundred ninety-eight million, one hundred eighty thousand, three hundred nine".