81978045 has 16 divisors (see below), whose sum is σ = 131594112. Its totient is φ = 43578560.

The previous prime is 81978023. The next prime is 81978053. The reversal of 81978045 is 54087918.

It is not a de Polignac number, because 81978045 - 2¹⁴ = 81961661 is a prime.

It is a junction number, because it is equal to n+sod(n) for n = 81977988 and 81978006.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 4122 + ... + 13451.

It is an arithmetic number, because the mean of its divisors is an integer number (8224632).

Almost surely, 2^81978045 is an apocalyptic number.

It is an amenable number.

81978045 is a deficient number, since it is larger than the sum of its proper divisors (49616067).

81978045 is a wasteful number, since it uses less digits than its factorization.

81978045 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 17892.

The product of its (nonzero) digits is 80640, while the sum is 42.

The square root of 81978045 is about 9054.1727949051. The cubic root of 81978045 is about 434.4093715016.

The spelling of 81978045 in words is "eighty-one million, nine hundred seventy-eight thousand, forty-five".