81939494 has 16 divisors (see below), whose sum is σ = 151273248. Its totient is φ = 32415552.

The previous prime is 81939463. The next prime is 81939503. The reversal of 81939494 is 49493918.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 224927 + ... + 225290.

It is an arithmetic number, because the mean of its divisors is an integer number (9454578).

Almost surely, 2^81939494 is an apocalyptic number.

81939494 is a deficient number, since it is larger than the sum of its proper divisors (69333754).

81939494 is a wasteful number, since it uses less digits than its factorization.

81939494 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 450239.

The product of its digits is 279936, while the sum is 47.

The square root of 81939494 is about 9052.0436366602. The cubic root of 81939494 is about 434.3412656996.

The spelling of 81939494 in words is "eighty-one million, nine hundred thirty-nine thousand, four hundred ninety-four".