81133613 has 8 divisors (see below), whose sum is σ = 89423040. Its totient is φ = 72996480.

The previous prime is 81133601. The next prime is 81133631. The reversal of 81133613 is 31633118.

It is a happy number.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81133613 - 2⁴ = 81133597 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 (81133643) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 36953 + ... + 39086.

It is an arithmetic number, because the mean of its divisors is an integer number (11177880).

Almost surely, 2^81133613 is an apocalyptic number.

It is an amenable number.

81133613 is a deficient number, since it is larger than the sum of its proper divisors (8289427).

81133613 is a wasteful number, since it uses less digits than its factorization.

81133613 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 76147.

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

The square root of 81133613 is about 9007.4198858497. The cubic root of 81133613 is about 432.9126456988.

The spelling of 81133613 in words is "eighty-one million, one hundred thirty-three thousand, six hundred thirteen".