81312861 has 8 divisors (see below), whose sum is σ = 123905344. Its totient is φ = 46464480.

The previous prime is 81312827. The next prime is 81312863. The reversal of 81312861 is 16821318.

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

It is not a de Polignac number, because 81312861 - 2⁷ = 81312733 is a prime.

It is a super-2 number, since 2×81312861² = 13223562728010642, which contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81312863) 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, 1936000 + ... + 1936041.

It is an arithmetic number, because the mean of its divisors is an integer number (15488168).

Almost surely, 2^81312861 is an apocalyptic number.

It is an amenable number.

81312861 is a deficient number, since it is larger than the sum of its proper divisors (42592483).

81312861 is a wasteful number, since it uses less digits than its factorization.

81312861 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3872051.

The product of its digits is 2304, while the sum is 30.

The square root of 81312861 is about 9017.3644153932. The cubic root of 81312861 is about 433.2312216337.

The spelling of 81312861 in words is "eighty-one million, three hundred twelve thousand, eight hundred sixty-one".