81445505 has 4 divisors (see below), whose sum is σ = 97734612. Its totient is φ = 65156400.

The previous prime is 81445489. The next prime is 81445517. The reversal of 81445505 is 50554418.

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 27804529 + 53640976 = 5273^2 + 7324^2 .

It is not a de Polignac number, because 81445505 - 2⁴ = 81445489 is a prime.

It is a Duffinian number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 8144546 + ... + 8144555.

It is an arithmetic number, because the mean of its divisors is an integer number (24433653).

Almost surely, 2^81445505 is an apocalyptic number.

It is an amenable number.

81445505 is a deficient number, since it is larger than the sum of its proper divisors (16289107).

81445505 is a wasteful number, since it uses less digits than its factorization.

81445505 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 16289106.

The product of its (nonzero) digits is 16000, while the sum is 32.

The square root of 81445505 is about 9024.7163390325. The cubic root of 81445505 is about 433.4666673852.

The spelling of 81445505 in words is "eighty-one million, four hundred forty-five thousand, five hundred five".