81831661 has 8 divisors (see below), whose sum is σ = 84801024. Its totient is φ = 78882960.

The previous prime is 81831647. The next prime is 81831691. The reversal of 81831661 is 16613818.

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 81831661 - 2¹¹ = 81829613 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 (81831611) 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, 3135 + ... + 13171.

It is an arithmetic number, because the mean of its divisors is an integer number (10600128).

Almost surely, 2^81831661 is an apocalyptic number.

It is an amenable number.

81831661 is a deficient number, since it is larger than the sum of its proper divisors (2969363).

81831661 is a wasteful number, since it uses less digits than its factorization.

81831661 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 10331.

The product of its digits is 6912, while the sum is 34.

The square root of 81831661 is about 9046.0853964574. The cubic root of 81831661 is about 434.1506499168.

The spelling of 81831661 in words is "eighty-one million, eight hundred thirty-one thousand, six hundred sixty-one".