81168209278 has 24 divisors (see below), whose sum is σ = 131859452448. Its totient is φ = 37456241472.

The previous prime is 81168209263. The next prime is 81168209293. The reversal of 81168209278 is 87290286118.

It is a happy number.

It is an interprime number because it is at equal distance from previous prime (81168209263) and next prime (81168209293).

It is a congruent number.

It is an unprimeable number.

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 11 ways as a sum of consecutive naturals, for example, 2628826 + ... + 2659522.

It is an arithmetic number, because the mean of its divisors is an integer number (5494143852).

Almost surely, 2^81168209278 is an apocalyptic number.

81168209278 is a deficient number, since it is larger than the sum of its proper divisors (50691243170).

81168209278 is a wasteful number, since it uses less digits than its factorization.

81168209278 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 38548 (or 38535 counting only the distinct ones).

The product of its (nonzero) digits is 774144, while the sum is 52.

The spelling of 81168209278 in words is "eighty-one billion, one hundred sixty-eight million, two hundred nine thousand, two hundred seventy-eight".