81402089 has 2 divisors, whose sum is σ = 81402090. Its totient is φ = 81402088.

The previous prime is 81402077. The next prime is 81402131. The reversal of 81402089 is 98020418.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 64320400 + 17081689 = 8020^2 + 4133^2 .

It is a cyclic number.

It is not a de Polignac number, because 81402089 - 2¹⁶ = 81336553 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81402019) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40701044 + 40701045.

It is an arithmetic number, because the mean of its divisors is an integer number (40701045).

Almost surely, 2^81402089 is an apocalyptic number.

It is an amenable number.

81402089 is a deficient number, since it is larger than the sum of its proper divisors (1).

81402089 is an equidigital number, since it uses as much as digits as its factorization.

81402089 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 4608, while the sum is 32.

The square root of 81402089 is about 9022.3106242248. The cubic root of 81402089 is about 433.3896312786.

The spelling of 81402089 in words is "eighty-one million, four hundred two thousand, eighty-nine".