81138878 has 8 divisors (see below), whose sum is σ = 121753368. Its totient is φ = 40554424.

The previous prime is 81138853. The next prime is 81138907. The reversal of 81138878 is 87883118.

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1325 + ... + 12807.

It is an arithmetic number, because the mean of its divisors is an integer number (15219171).

Almost surely, 2^81138878 is an apocalyptic number.

81138878 is a deficient number, since it is larger than the sum of its proper divisors (40614490).

81138878 is a wasteful number, since it uses less digits than its factorization.

81138878 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 15018.

The product of its digits is 86016, while the sum is 44.

The square root of 81138878 is about 9007.7121401608. The cubic root of 81138878 is about 432.9220098234.

The spelling of 81138878 in words is "eighty-one million, one hundred thirty-eight thousand, eight hundred seventy-eight".