81328005 has 24 divisors (see below), whose sum is σ = 153784800. Its totient is φ = 39431520.

The previous prime is 81327997. The next prime is 81328057. The reversal of 81328005 is 50082318.

It is a happy number.

It is not a de Polignac number, because 81328005 - 2³ = 81327997 is a prime.

It is a super-2 number, since 2×81328005² = 13228488794560050, which contains 22 as substring.

It is a self number, because there is not a number n which added to its sum of digits gives 81328005.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 81655 + ... + 82644.

It is an arithmetic number, because the mean of its divisors is an integer number (6407700).

Almost surely, 2^81328005 is an apocalyptic number.

It is an amenable number.

81328005 is a deficient number, since it is larger than the sum of its proper divisors (72456795).

81328005 is a wasteful number, since it uses less digits than its factorization.

81328005 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 164321 (or 164318 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 27.

The square root of 81328005 is about 9018.2040895070. The cubic root of 81328005 is about 433.2581154783.

It can be divided in two parts, 81 and 328005, that multiplied together give a triangular number (26568405 = T₇₂₈₉).

The spelling of 81328005 in words is "eighty-one million, three hundred twenty-eight thousand, five".