81951313 has 8 divisors (see below), whose sum is σ = 86649120. Its totient is φ = 77292000.

The previous prime is 81951301. The next prime is 81951319. The reversal of 81951313 is 31315918.

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

It is not a de Polignac number, because 81951313 - 2⁹ = 81950801 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81951319) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 5188 + ... + 13813.

It is an arithmetic number, because the mean of its divisors is an integer number (10831140).

Almost surely, 2^81951313 is an apocalyptic number.

It is an amenable number.

81951313 is a deficient number, since it is larger than the sum of its proper divisors (4697807).

81951313 is a wasteful number, since it uses less digits than its factorization.

81951313 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 19247.

The product of its digits is 3240, while the sum is 31.

The square root of 81951313 is about 9052.6964491250. The cubic root of 81951313 is about 434.3621479074.

The spelling of 81951313 in words is "eighty-one million, nine hundred fifty-one thousand, three hundred thirteen".