81978426 has 32 divisors (see below), whose sum is σ = 191764800. Its totient is φ = 25887600.

The previous prime is 81978401. The next prime is 81978431. The reversal of 81978426 is 62487918.

It is a Curzon number.

It is an unprimeable number.

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, 38925 + ... + 40976.

It is an arithmetic number, because the mean of its divisors is an integer number (5992650).

Almost surely, 2^81978426 is an apocalyptic number.

81978426 is an abundant number, since it is smaller than the sum of its proper divisors (109786374).

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

81978426 is a wasteful number, since it uses less digits than its factorization.

81978426 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 79931 (or 79925 counting only the distinct ones).

The product of its digits is 193536, while the sum is 45.

The square root of 81978426 is about 9054.1938349032. The cubic root of 81978426 is about 434.4100444855.

The spelling of 81978426 in words is "eighty-one million, nine hundred seventy-eight thousand, four hundred twenty-six".