81501831 has 6 divisors (see below), whose sum is σ = 117724880. Its totient is φ = 54334548.

The previous prime is 81501779. The next prime is 81501881. The reversal of 81501831 is 13810518.

81501831 is a `hidden beast` number, since 81 + 501 + 83 + 1 = 666.

It is not a de Polignac number, because 81501831 - 2¹¹ = 81499783 is a prime.

It is a super-2 number, since 2×81501831² = 13285096912705122, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 81501795 and 81501804.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81501881) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 4527871 + ... + 4527888.

Almost surely, 2^81501831 is an apocalyptic number.

81501831 is a deficient number, since it is larger than the sum of its proper divisors (36223049).

81501831 is a wasteful number, since it uses less digits than its factorization.

81501831 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 9055765 (or 9055762 counting only the distinct ones).

The product of its (nonzero) digits is 960, while the sum is 27.

The square root of 81501831 is about 9027.8364517751. The cubic root of 81501831 is about 433.5665698385.

The spelling of 81501831 in words is "eighty-one million, five hundred one thousand, eight hundred thirty-one".