81131145 has 16 divisors (see below), whose sum is σ = 131025600. Its totient is φ = 42864704.

The previous prime is 81131137. The next prime is 81131147. The reversal of 81131145 is 54113118.

It is a cyclic number.

It is not a de Polignac number, because 81131145 - 2³ = 81131137 is a prime.

It is a super-2 number, since 2×81131145² = 13164525378022050, which contains 22 as substring.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81131147) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 23670 + ... + 26879.

It is an arithmetic number, because the mean of its divisors is an integer number (8189100).

Almost surely, 2^81131145 is an apocalyptic number.

It is an amenable number.

81131145 is a deficient number, since it is larger than the sum of its proper divisors (49894455).

81131145 is a wasteful number, since it uses less digits than its factorization.

81131145 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 50664.

The product of its digits is 480, while the sum is 24.

The square root of 81131145 is about 9007.2828866423. The cubic root of 81131145 is about 432.9082560704.

The spelling of 81131145 in words is "eighty-one million, one hundred thirty-one thousand, one hundred forty-five".