81647806 has 8 divisors (see below), whose sum is σ = 122633280. Its totient is φ = 40770048.

The previous prime is 81647777. The next prime is 81647827. The reversal of 81647806 is 60874618.

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

It is a super-2 number, since 2×81647806² = 13332728449227272, which contains 22 as substring.

It is a congruent number.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 25006 + ... + 28081.

It is an arithmetic number, because the mean of its divisors is an integer number (15329160).

Almost surely, 2^81647806 is an apocalyptic number.

81647806 is a deficient number, since it is larger than the sum of its proper divisors (40985474).

81647806 is a wasteful number, since it uses less digits than its factorization.

81647806 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 53858.

The product of its (nonzero) digits is 64512, while the sum is 40.

The square root of 81647806 is about 9035.9175516380. The cubic root of 81647806 is about 433.8252639537.

The spelling of 81647806 in words is "eighty-one million, six hundred forty-seven thousand, eight hundred six".