81315831 has 8 divisors (see below), whose sum is σ = 108471024. Its totient is φ = 54185600.

The previous prime is 81315809. The next prime is 81315841. The reversal of 81315831 is 13851318.

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 81315831 - 2⁵ = 81315799 is a prime.

It is a super-2 number, since 2×81315831² = 13224528742441122, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81315841) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 3565 + ... + 13241.

It is an arithmetic number, because the mean of its divisors is an integer number (13558878).

Almost surely, 2^81315831 is an apocalyptic number.

81315831 is a deficient number, since it is larger than the sum of its proper divisors (27155193).

81315831 is a wasteful number, since it uses less digits than its factorization.

81315831 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 12481.

The product of its digits is 2880, while the sum is 30.

The square root of 81315831 is about 9017.5290961549. The cubic root of 81315831 is about 433.2364962444.

The spelling of 81315831 in words is "eighty-one million, three hundred fifteen thousand, eight hundred thirty-one".