81455989 has 2 divisors, whose sum is σ = 81455990. Its totient is φ = 81455988.

The previous prime is 81455977. The next prime is 81456007. The reversal of 81455989 is 98955418.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 49815364 + 31640625 = 7058^2 + 5625^2 .

It is a cyclic number.

It is not a de Polignac number, because 81455989 - 2⁷ = 81455861 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (81455929) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40727994 + 40727995.

It is an arithmetic number, because the mean of its divisors is an integer number (40727995).

Almost surely, 2^81455989 is an apocalyptic number.

It is an amenable number.

81455989 is a deficient number, since it is larger than the sum of its proper divisors (1).

81455989 is an equidigital number, since it uses as much as digits as its factorization.

81455989 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 518400, while the sum is 49.

The square root of 81455989 is about 9025.2971696227. The cubic root of 81455989 is about 433.4852657906.

The spelling of 81455989 in words is "eighty-one million, four hundred fifty-five thousand, nine hundred eighty-nine".