81785893 has 8 divisors (see below), whose sum is σ = 93804480. Its totient is φ = 69851040.

The previous prime is 81785863. The next prime is 81785917. The reversal of 81785893 is 39858718.

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-81785893 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81785833) 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, 18823 + ... + 22756.

It is an arithmetic number, because the mean of its divisors is an integer number (11725560).

Almost surely, 2^81785893 is an apocalyptic number.

It is an amenable number.

81785893 is a deficient number, since it is larger than the sum of its proper divisors (12018587).

81785893 is a wasteful number, since it uses less digits than its factorization.

81785893 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 41867.

The product of its digits is 483840, while the sum is 49.

The square root of 81785893 is about 9043.5553296256. Note that the first 3 decimals coincide. The cubic root of 81785893 is about 434.0696954619.

The spelling of 81785893 in words is "eighty-one million, seven hundred eighty-five thousand, eight hundred ninety-three".