81131895 has 32 divisors (see below), whose sum is σ = 155332800. Its totient is φ = 39940992.

The previous prime is 81131893. The next prime is 81131899. The reversal of 81131895 is 59813118.

It is not a de Polignac number, because 81131895 - 2¹ = 81131893 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81131893) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 21360 + ... + 24869.

It is an arithmetic number, because the mean of its divisors is an integer number (4854150).

Almost surely, 2^81131895 is an apocalyptic number.

81131895 is a deficient number, since it is larger than the sum of its proper divisors (74200905).

81131895 is a wasteful number, since it uses less digits than its factorization.

81131895 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 46256 (or 46250 counting only the distinct ones).

The product of its digits is 8640, while the sum is 36.

The square root of 81131895 is about 9007.3245195230. The cubic root of 81131895 is about 432.9095900431.

The spelling of 81131895 in words is "eighty-one million, one hundred thirty-one thousand, eight hundred ninety-five".