81281506 has 8 divisors (see below), whose sum is σ = 128339280. Its totient is φ = 38501748.

The previous prime is 81281503. The next prime is 81281507. The reversal of 81281506 is 60518218.

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

It is not an unprimeable number, because it can be changed into a prime (81281503) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1069456 + ... + 1069531.

It is an arithmetic number, because the mean of its divisors is an integer number (16042410).

Almost surely, 2^81281506 is an apocalyptic number.

81281506 is a deficient number, since it is larger than the sum of its proper divisors (47057774).

81281506 is a wasteful number, since it uses less digits than its factorization.

81281506 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2139008.

The product of its (nonzero) digits is 3840, while the sum is 31.

The square root of 81281506 is about 9015.6256577123. The cubic root of 81281506 is about 433.1755284703.

The spelling of 81281506 in words is "eighty-one million, two hundred eighty-one thousand, five hundred six".