81665120233 has 2 divisors, whose sum is σ = 81665120234. Its totient is φ = 81665120232.

The previous prime is 81665120189. The next prime is 81665120263. The reversal of 81665120233 is 33202156618.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 81503398144 + 161722089 = 285488^2 + 12717^2 .

It is a cyclic number.

It is not a de Polignac number, because 81665120233 - 2²¹ = 81663023081 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81665120192 and 81665120201.

It is not a weakly prime, because it can be changed into another prime (81665120263) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40832560116 + 40832560117.

It is an arithmetic number, because the mean of its divisors is an integer number (40832560117).

Almost surely, 2^81665120233 is an apocalyptic number.

It is an amenable number.

81665120233 is a deficient number, since it is larger than the sum of its proper divisors (1).

81665120233 is an equidigital number, since it uses as much as digits as its factorization.

81665120233 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 51840, while the sum is 37.

The spelling of 81665120233 in words is "eighty-one billion, six hundred sixty-five million, one hundred twenty thousand, two hundred thirty-three".