81509996 has 6 divisors (see below), whose sum is σ = 142642500. Its totient is φ = 40754996.

The previous prime is 81509971. The next prime is 81510007. The reversal of 81509996 is 69990518.

It is a self number, because there is not a number n which added to its sum of digits gives 81509996.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10188746 + ... + 10188753.

It is an arithmetic number, because the mean of its divisors is an integer number (23773750).

Almost surely, 2^81509996 is an apocalyptic number.

It is an amenable number.

81509996 is a deficient number, since it is larger than the sum of its proper divisors (61132504).

81509996 is a wasteful number, since it uses less digits than its factorization.

81509996 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 20377503 (or 20377501 counting only the distinct ones).

The product of its (nonzero) digits is 174960, while the sum is 47.

The square root of 81509996 is about 9028.2886528954. The cubic root of 81509996 is about 433.5810478479.

The spelling of 81509996 in words is "eighty-one million, five hundred nine thousand, nine hundred ninety-six".