81778167744 has 112 divisors (see below), whose sum is σ = 266303321088. Its totient is φ = 21567863808.

The previous prime is 81778167719. The next prime is 81778167763. The reversal of 81778167744 is 44776187718.

It is a tau number, because it is divible by the number of its divisors (112).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 2322792 + ... + 2357735.

It is an arithmetic number, because the mean of its divisors is an integer number (2377708224).

Almost surely, 2^81778167744 is an apocalyptic number.

81778167744 is a gapful number since it is divisible by the number (84) formed by its first and last digit.

It is an amenable number.

81778167744 is an abundant number, since it is smaller than the sum of its proper divisors (184525153344).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81778167744 is a wasteful number, since it uses less digits than its factorization.

81778167744 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4680562 (or 4680552 counting only the distinct ones).

The product of its digits is 14751744, while the sum is 60.

The spelling of 81778167744 in words is "eighty-one billion, seven hundred seventy-eight million, one hundred sixty-seven thousand, seven hundred forty-four".