81481489 has 4 divisors (see below), whose sum is σ = 81775924. Its totient is φ = 81187056.

The previous prime is 81481487. The next prime is 81481501. The reversal of 81481489 is 98418418.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 3900625 + 77580864 = 1975^2 + 8808^2 .

It is a cyclic number.

It is not a de Polignac number, because 81481489 - 2¹ = 81481487 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81481483) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 146802 + ... + 147355.

It is an arithmetic number, because the mean of its divisors is an integer number (20443981).

Almost surely, 2^81481489 is an apocalyptic number.

It is an amenable number.

81481489 is a deficient number, since it is larger than the sum of its proper divisors (294435).

81481489 is a wasteful number, since it uses less digits than its factorization.

81481489 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 294434.

The product of its digits is 73728, while the sum is 43.

The square root of 81481489 is about 9026.7097549439. The cubic root of 81481489 is about 433.5304956181.

The spelling of 81481489 in words is "eighty-one million, four hundred eighty-one thousand, four hundred eighty-nine".