81965633 has 2 divisors, whose sum is σ = 81965634. Its totient is φ = 81965632.

The previous prime is 81965627. The next prime is 81965647. The reversal of 81965633 is 33656918.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 81306289 + 659344 = 9017^2 + 812^2 .

It is a cyclic number.

It is not a de Polignac number, because 81965633 - 2¹⁶ = 81900097 is a prime.

It is a Sophie Germain prime.

It is a Chen prime.

It is a Curzon number.

It is not a weakly prime, because it can be changed into another prime (81965833) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40982816 + 40982817.

It is an arithmetic number, because the mean of its divisors is an integer number (40982817).

Almost surely, 2^81965633 is an apocalyptic number.

It is an amenable number.

81965633 is a deficient number, since it is larger than the sum of its proper divisors (1).

81965633 is an equidigital number, since it uses as much as digits as its factorization.

81965633 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 116640, while the sum is 41.

The square root of 81965633 is about 9053.4873391418. The cubic root of 81965633 is about 434.3874462766.

The spelling of 81965633 in words is "eighty-one million, nine hundred sixty-five thousand, six hundred thirty-three".