81131745 has 16 divisors (see below), whose sum is σ = 130299840. Its totient is φ = 43107264.

The previous prime is 81131737. The next prime is 81131747. The reversal of 81131745 is 54713118.

It is not a de Polignac number, because 81131745 - 2³ = 81131737 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81131747) 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, 6019 + ... + 14088.

It is an arithmetic number, because the mean of its divisors is an integer number (8143740).

Almost surely, 2^81131745 is an apocalyptic number.

It is an amenable number.

81131745 is a deficient number, since it is larger than the sum of its proper divisors (49168095).

81131745 is a wasteful number, since it uses less digits than its factorization.

81131745 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20384.

The product of its digits is 3360, while the sum is 30.

The square root of 81131745 is about 9007.3161929623. The cubic root of 81131745 is about 432.9093232492.

The spelling of 81131745 in words is "eighty-one million, one hundred thirty-one thousand, seven hundred forty-five".