81764815 has 32 divisors (see below), whose sum is σ = 114260544. Its totient is φ = 55511040.

The previous prime is 81764791. The next prime is 81764869. The reversal of 81764815 is 51846718.

It is not a de Polignac number, because 81764815 - 2⁷ = 81764687 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

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 31 ways as a sum of consecutive naturals, for example, 146517 + ... + 147073.

It is an arithmetic number, because the mean of its divisors is an integer number (3570642).

Almost surely, 2^81764815 is an apocalyptic number.

81764815 is a gapful number since it is divisible by the number (85) formed by its first and last digit.

81764815 is a deficient number, since it is larger than the sum of its proper divisors (32495729).

81764815 is a wasteful number, since it uses less digits than its factorization.

81764815 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 747.

The product of its digits is 53760, while the sum is 40.

The square root of 81764815 is about 9042.3898942702. The cubic root of 81764815 is about 434.0324025303.

The spelling of 81764815 in words is "eighty-one million, seven hundred sixty-four thousand, eight hundred fifteen".