81855537 has 8 divisors (see below), whose sum is σ = 109249920. Its totient is φ = 54515760.

The previous prime is 81855523. The next prime is 81855547. The reversal of 81855537 is 73555818.

It is a happy number.

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

It is a de Polignac number, because none of the positive numbers 2^k-81855537 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81855517) 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, 10014 + ... + 16247.

It is an arithmetic number, because the mean of its divisors is an integer number (13656240).

Almost surely, 2^81855537 is an apocalyptic number.

It is an amenable number.

81855537 is a deficient number, since it is larger than the sum of its proper divisors (27394383).

81855537 is a wasteful number, since it uses less digits than its factorization.

81855537 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 27303.

The product of its digits is 168000, while the sum is 42.

The square root of 81855537 is about 9047.4049870667. The cubic root of 81855537 is about 434.1928698140.

The spelling of 81855537 in words is "eighty-one million, eight hundred fifty-five thousand, five hundred thirty-seven".