81978854 has 16 divisors (see below), whose sum is σ = 130077792. Its totient is φ = 38668608.

The previous prime is 81978839. The next prime is 81978887. The reversal of 81978854 is 45887918.

It is a Curzon number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 8849 + ... + 15564.

It is an arithmetic number, because the mean of its divisors is an integer number (8129862).

Almost surely, 2^81978854 is an apocalyptic number.

81978854 is a deficient number, since it is larger than the sum of its proper divisors (48098938).

81978854 is a wasteful number, since it uses less digits than its factorization.

81978854 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 24511.

The product of its digits is 645120, while the sum is 50.

The square root of 81978854 is about 9054.2174703284. The cubic root of 81978854 is about 434.4108004860.

The spelling of 81978854 in words is "eighty-one million, nine hundred seventy-eight thousand, eight hundred fifty-four".