81647313 has 32 divisors (see below), whose sum is σ = 126282240. Its totient is φ = 46402560.

The previous prime is 81647303. The next prime is 81647329. The reversal of 81647313 is 31374618.

It is not a de Polignac number, because 81647313 - 2¹⁰ = 81646289 is a prime.

It is a Harshad number since it is a multiple of its sum of digits (33).

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81647303) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 66481 + ... + 67697.

It is an arithmetic number, because the mean of its divisors is an integer number (3946320).

Almost surely, 2^81647313 is an apocalyptic number.

It is an amenable number.

81647313 is a deficient number, since it is larger than the sum of its proper divisors (44634927).

81647313 is a wasteful number, since it uses less digits than its factorization.

81647313 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1357.

The product of its digits is 12096, while the sum is 33.

The square root of 81647313 is about 9035.8902715781. The cubic root of 81647313 is about 433.8243907876.

The spelling of 81647313 in words is "eighty-one million, six hundred forty-seven thousand, three hundred thirteen".