81167778 has 32 divisors (see below), whose sum is σ = 184216320. Its totient is φ = 26479440.

The previous prime is 81167771. The next prime is 81167783. The reversal of 81167778 is 87776118.

It is a happy number.

It is a Curzon number.

It is not an unprimeable number, because it can be changed into a prime (81167771) 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, 13453 + ... + 18528.

It is an arithmetic number, because the mean of its divisors is an integer number (5756760).

Almost surely, 2^81167778 is an apocalyptic number.

81167778 is an abundant number, since it is smaller than the sum of its proper divisors (103048542).

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

81167778 is a wasteful number, since it uses less digits than its factorization.

81167778 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 32039 (or 32033 counting only the distinct ones).

The product of its digits is 131712, while the sum is 45.

The square root of 81167778 is about 9009.3161782679. The cubic root of 81167778 is about 432.9734030283.

The spelling of 81167778 in words is "eighty-one million, one hundred sixty-seven thousand, seven hundred seventy-eight".