81428489 has 2 divisors, whose sum is σ = 81428490. Its totient is φ = 81428488.

The previous prime is 81428483. The next prime is 81428497. The reversal of 81428489 is 98482418.

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., 75342400 + 6086089 = 8680^2 + 2467^2 .

It is a cyclic number.

It is not a de Polignac number, because 81428489 - 2²⁰ = 80379913 is a prime.

It is a Chen prime.

It is not a weakly prime, because it can be changed into another prime (81428483) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40714244 + 40714245.

It is an arithmetic number, because the mean of its divisors is an integer number (40714245).

Almost surely, 2^81428489 is an apocalyptic number.

It is an amenable number.

81428489 is a deficient number, since it is larger than the sum of its proper divisors (1).

81428489 is an equidigital number, since it uses as much as digits as its factorization.

81428489 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 147456, while the sum is 44.

The square root of 81428489 is about 9023.7735454742. The cubic root of 81428489 is about 433.4364779453.

The spelling of 81428489 in words is "eighty-one million, four hundred twenty-eight thousand, four hundred eighty-nine".