81909896 has 8 divisors (see below), whose sum is σ = 153581070. Its totient is φ = 40954944.

The previous prime is 81909887. The next prime is 81909899. The reversal of 81909896 is 69890918.

It can be written as a sum of positive squares in only one way, i.e., 81902500 + 7396 = 9050^2 + 86^2 .

It is a tau number, because it is divible by the number of its divisors (8).

It is not an unprimeable number, because it can be changed into a prime (81909899) by changing a digit.

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 as a sum of consecutive naturals, namely, 5119361 + ... + 5119376.

Almost surely, 2^81909896 is an apocalyptic number.

It is an amenable number.

81909896 is a deficient number, since it is larger than the sum of its proper divisors (71671174).

81909896 is a wasteful number, since it uses less digits than its factorization.

81909896 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 10238743 (or 10238739 counting only the distinct ones).

The product of its (nonzero) digits is 279936, while the sum is 50.

The square root of 81909896 is about 9050.4086095601. The cubic root of 81909896 is about 434.2889621426.

The spelling of 81909896 in words is "eighty-one million, nine hundred nine thousand, eight hundred ninety-six".