81409936 has 10 divisors (see below), whose sum is σ = 157731782. Its totient is φ = 40704960.

The previous prime is 81409907. The next prime is 81409943. The reversal of 81409936 is 63990418.

It can be written as a sum of positive squares in only one way, i.e., 72999936 + 8410000 = 8544^2 + 2900^2 .

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 as a sum of consecutive naturals, namely, 2544045 + ... + 2544076.

Almost surely, 2^81409936 is an apocalyptic number.

It is an amenable number.

81409936 is a deficient number, since it is larger than the sum of its proper divisors (76321846).

81409936 is a wasteful number, since it uses less digits than its factorization.

81409936 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5088129 (or 5088123 counting only the distinct ones).

The product of its (nonzero) digits is 46656, while the sum is 40.

The square root of 81409936 is about 9022.7454801740. The cubic root of 81409936 is about 433.4035567982.

The spelling of 81409936 in words is "eighty-one million, four hundred nine thousand, nine hundred thirty-six".