81210289 has 2 divisors, whose sum is σ = 81210290. Its totient is φ = 81210288.

The previous prime is 81210281. The next prime is 81210307. The reversal of 81210289 is 98201218.

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., 53173264 + 28037025 = 7292^2 + 5295^2 .

It is a cyclic number.

It is not a de Polignac number, because 81210289 - 2³ = 81210281 is a prime.

It is a super-2 number, since 2×81210289² = 13190222078927042, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 81210289.

It is not a weakly prime, because it can be changed into another prime (81210281) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40605144 + 40605145.

It is an arithmetic number, because the mean of its divisors is an integer number (40605145).

Almost surely, 2^81210289 is an apocalyptic number.

It is an amenable number.

81210289 is a deficient number, since it is larger than the sum of its proper divisors (1).

81210289 is an equidigital number, since it uses as much as digits as its factorization.

81210289 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2304, while the sum is 31.

The square root of 81210289 is about 9011.6751494936. The cubic root of 81210289 is about 433.0489786667.

The spelling of 81210289 in words is "eighty-one million, two hundred ten thousand, two hundred eighty-nine".