81281013 has 32 divisors (see below), whose sum is σ = 121347072. Its totient is φ = 47980800.

The previous prime is 81280981. The next prime is 81281017. The reversal of 81281013 is 31018218.

It is not a de Polignac number, because 81281013 - 2⁵ = 81280981 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81281017) 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 31 ways as a sum of consecutive naturals, for example, 264606 + ... + 264912.

It is an arithmetic number, because the mean of its divisors is an integer number (3792096).

Almost surely, 2^81281013 is an apocalyptic number.

It is an amenable number.

81281013 is a deficient number, since it is larger than the sum of its proper divisors (40066059).

81281013 is a wasteful number, since it uses less digits than its factorization.

81281013 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 505.

The product of its (nonzero) digits is 384, while the sum is 24.

The square root of 81281013 is about 9015.5983162517. The cubic root of 81281013 is about 433.1746526828.

The spelling of 81281013 in words is "eighty-one million, two hundred eighty-one thousand, thirteen".