81312478 has 8 divisors (see below), whose sum is σ = 131350968. Its totient is φ = 37528824.

The previous prime is 81312461. The next prime is 81312493. The reversal of 81312478 is 87421318.

It is a happy number.

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

It is a super-2 number, since 2×81312478² = 13223438157000968, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1563676 + ... + 1563727.

It is an arithmetic number, because the mean of its divisors is an integer number (16418871).

Almost surely, 2^81312478 is an apocalyptic number.

81312478 is a deficient number, since it is larger than the sum of its proper divisors (50038490).

81312478 is a wasteful number, since it uses less digits than its factorization.

81312478 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3127418.

The product of its digits is 10752, while the sum is 34.

The square root of 81312478 is about 9017.3431785643. The cubic root of 81312478 is about 433.2305414304.

It can be divided in two parts, 8131 and 2478, that added together give a square (10609 = 103²).

The spelling of 81312478 in words is "eighty-one million, three hundred twelve thousand, four hundred seventy-eight".