81139378 has 8 divisors (see below), whose sum is σ = 121882860. Its totient is φ = 40511760.

The previous prime is 81139363. The next prime is 81139391. The reversal of 81139378 is 87393118.

It can be written as a sum of positive squares in 2 ways, for example, as 79441569 + 1697809 = 8913^2 + 1303^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is a self number, because there is not a number n which added to its sum of digits gives 81139378.

It is an unprimeable number.

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 3 ways as a sum of consecutive naturals, for example, 27193 + ... + 30028.

Almost surely, 2^81139378 is an apocalyptic number.

81139378 is a deficient number, since it is larger than the sum of its proper divisors (40743482).

81139378 is a wasteful number, since it uses less digits than its factorization.

81139378 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 57932.

The product of its digits is 36288, while the sum is 40.

The square root of 81139378 is about 9007.7398941133. The cubic root of 81139378 is about 432.9228990829.

The spelling of 81139378 in words is "eighty-one million, one hundred thirty-nine thousand, three hundred seventy-eight".