81312424 has 16 divisors (see below), whose sum is σ = 152579700. Its totient is φ = 40624512.

The previous prime is 81312367. The next prime is 81312461. The reversal of 81312424 is 42421318.

It can be written as a sum of positive squares in 2 ways, for example, as 72420100 + 8892324 = 8510^2 + 2982^2 .

It is a super-2 number, since 2×81312424² = 13223420593511552, which contains 22 as substring.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 9714 + ... + 16030.

Almost surely, 2^81312424 is an apocalyptic number.

It is an amenable number.

81312424 is a deficient number, since it is larger than the sum of its proper divisors (71267276).

81312424 is a wasteful number, since it uses less digits than its factorization.

81312424 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7932 (or 7928 counting only the distinct ones).

The product of its digits is 1536, while the sum is 25.

The square root of 81312424 is about 9017.3401843337. The cubic root of 81312424 is about 433.2304455269.

The spelling of 81312424 in words is "eighty-one million, three hundred twelve thousand, four hundred twenty-four".