81136133 has 4 divisors (see below), whose sum is σ = 87377388. Its totient is φ = 74894880.

The previous prime is 81136103. The next prime is 81136169. The reversal of 81136133 is 33163118.

It is a happy number.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 20638849 + 60497284 = 4543^2 + 7778^2 .

It is a cyclic number.

It is not a de Polignac number, because 81136133 - 2⁸ = 81135877 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81136103) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3120608 + ... + 3120633.

It is an arithmetic number, because the mean of its divisors is an integer number (21844347).

Almost surely, 2^81136133 is an apocalyptic number.

It is an amenable number.

81136133 is a deficient number, since it is larger than the sum of its proper divisors (6241255).

81136133 is a wasteful number, since it uses less digits than its factorization.

81136133 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6241254.

The product of its digits is 1296, while the sum is 26.

The square root of 81136133 is about 9007.5597694381. The cubic root of 81136133 is about 432.9171277235.

The spelling of 81136133 in words is "eighty-one million, one hundred thirty-six thousand, one hundred thirty-three".