81085731 has 8 divisors (see below), whose sum is σ = 108155904. Its totient is φ = 54036360.

The previous prime is 81085727. The next prime is 81085757. The reversal of 81085731 is 13758018.

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

It is not a de Polignac number, because 81085731 - 2² = 81085727 is a prime.

It is a super-2 number, since 2×81085731² = 13149791543608722, which contains 22 as substring.

It is a Smith number, since the sum of its digits (33) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a junction number, because it is equal to n+sod(n) for n = 81085692 and 81085701.

It is not an unprimeable number, because it can be changed into a prime (81085721) 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, 12886 + ... + 18116.

It is an arithmetic number, because the mean of its divisors is an integer number (13519488).

Almost surely, 2^81085731 is an apocalyptic number.

81085731 is a deficient number, since it is larger than the sum of its proper divisors (27070173).

81085731 is a wasteful number, since it uses less digits than its factorization.

81085731 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10401.

The product of its (nonzero) digits is 6720, while the sum is 33.

The square root of 81085731 is about 9004.7615737453. The cubic root of 81085731 is about 432.8274660319.

The spelling of 81085731 in words is "eighty-one million, eighty-five thousand, seven hundred thirty-one".