81969390899 has 16 divisors (see below), whose sum is σ = 90364686720. Its totient is φ = 73731720960.

The previous prime is 81969390889. The next prime is 81969390947. The reversal of 81969390899 is 99809396918.

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-81969390899 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81969390889) by changing a digit.

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 in 15 ways as a sum of consecutive naturals, for example, 6800372 + ... + 6812414.

It is an arithmetic number, because the mean of its divisors is an integer number (5647792920).

Almost surely, 2^81969390899 is an apocalyptic number.

81969390899 is a deficient number, since it is larger than the sum of its proper divisors (8395295821).

81969390899 is a wasteful number, since it uses less digits than its factorization.

81969390899 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 18530.

The product of its (nonzero) digits is 68024448, while the sum is 71.

The spelling of 81969390899 in words is "eighty-one billion, nine hundred sixty-nine million, three hundred ninety thousand, eight hundred ninety-nine".