81456813 has 16 divisors (see below), whose sum is σ = 122955840. Its totient is φ = 53278992.

The previous prime is 81456811. The next prime is 81456833. The reversal of 81456813 is 31865418.

81456813 is a `hidden beast` number, since 81 + 4 + 568 + 13 = 666.

It is not a de Polignac number, because 81456813 - 2¹ = 81456811 is a prime.

It is a hoax number, since the sum of its digits (36) coincides with the sum of the digits of its distinct prime factors.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81456811) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 27031 + ... + 29892.

It is an arithmetic number, because the mean of its divisors is an integer number (7684740).

Almost surely, 2^81456813 is an apocalyptic number.

It is an amenable number.

81456813 is a deficient number, since it is larger than the sum of its proper divisors (41499027).

81456813 is a wasteful number, since it uses less digits than its factorization.

81456813 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 56985 (or 56979 counting only the distinct ones).

The product of its digits is 23040, while the sum is 36.

The square root of 81456813 is about 9025.3428189737. The cubic root of 81456813 is about 433.4867274824.

The spelling of 81456813 in words is "eighty-one million, four hundred fifty-six thousand, eight hundred thirteen".