81923764778 has 32 divisors (see below), whose sum is σ = 124910843904. Its totient is φ = 40293796032.

The previous prime is 81923764777. The next prime is 81923764789. The reversal of 81923764778 is 87746732918.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 81923764778.

It is not an unprimeable number, because it can be changed into a prime (81923764777) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 15359000 + ... + 15364332.

It is an arithmetic number, because the mean of its divisors is an integer number (3903463872).

Almost surely, 2^81923764778 is an apocalyptic number.

81923764778 is a deficient number, since it is larger than the sum of its proper divisors (42987079126).

81923764778 is a wasteful number, since it uses less digits than its factorization.

81923764778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5966.

The product of its digits is 28449792, while the sum is 62.

The spelling of 81923764778 in words is "eighty-one billion, nine hundred twenty-three million, seven hundred sixty-four thousand, seven hundred seventy-eight".