81978006 has 32 divisors (see below), whose sum is σ = 179424000. Its totient is φ = 24763680.

The previous prime is 81977947. The next prime is 81978007. The reversal of 81978006 is 60087918.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81978007) by changing a digit.

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 15 ways as a sum of consecutive naturals, for example, 21255 + ... + 24813.

It is an arithmetic number, because the mean of its divisors is an integer number (5607000).

Almost surely, 2^81978006 is an apocalyptic number.

81978006 is an abundant number, since it is smaller than the sum of its proper divisors (97445994).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81978006 is a wasteful number, since it uses less digits than its factorization.

81978006 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3924.

The product of its (nonzero) digits is 24192, while the sum is 39.

The square root of 81978006 is about 9054.1706412018. The cubic root of 81978006 is about 434.4093026134.

The spelling of 81978006 in words is "eighty-one million, nine hundred seventy-eight thousand, six".