81784313 has 8 divisors (see below), whose sum is σ = 88152456. Its totient is φ = 75427200.

The previous prime is 81784301. The next prime is 81784327. The reversal of 81784313 is 31348718.

It can be written as a sum of positive squares in 4 ways, for example, as 12694969 + 69089344 = 3563^2 + 8312^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81784313 - 2⁸ = 81784057 is a prime.

It is a Duffinian number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81784363) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 19133 + ... + 23013.

It is an arithmetic number, because the mean of its divisors is an integer number (11019057).

Almost surely, 2^81784313 is an apocalyptic number.

It is an amenable number.

81784313 is a deficient number, since it is larger than the sum of its proper divisors (6368143).

81784313 is a wasteful number, since it uses less digits than its factorization.

81784313 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 5515.

The product of its digits is 16128, while the sum is 35.

The square root of 81784313 is about 9043.4679741789. The cubic root of 81784313 is about 434.0669002181.

The spelling of 81784313 in words is "eighty-one million, seven hundred eighty-four thousand, three hundred thirteen".