81774051778 has 16 divisors (see below), whose sum is σ = 133281987840. Its totient is φ = 37485558000.

The previous prime is 81774051773. The next prime is 81774051787. The reversal of 81774051778 is 87715047718.

It is a happy number.

It is a super-2 number, since 2×81774051778² (a number of 23 digits) contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (81774051773) by changing a digit.

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 in 7 ways as a sum of consecutive naturals, for example, 34707673 + ... + 34710028.

It is an arithmetic number, because the mean of its divisors is an integer number (8330124240).

Almost surely, 2^81774051778 is an apocalyptic number.

81774051778 is a deficient number, since it is larger than the sum of its proper divisors (51507936062).

81774051778 is a wasteful number, since it uses less digits than its factorization.

81774051778 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 69417753.

The product of its (nonzero) digits is 3073280, while the sum is 55.

The spelling of 81774051778 in words is "eighty-one billion, seven hundred seventy-four million, fifty-one thousand, seven hundred seventy-eight".