81138379 has 8 divisors (see below), whose sum is σ = 97610240. Its totient is φ = 65886696.

The previous prime is 81138371. The next prime is 81138383. The reversal of 81138379 is 97383118.

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

It is a cyclic number.

It is not a de Polignac number, because 81138379 - 2³ = 81138371 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81138371) by changing a digit.

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 7 ways as a sum of consecutive naturals, for example, 304899 + ... + 305164.

It is an arithmetic number, because the mean of its divisors is an integer number (12201280).

Almost surely, 2^81138379 is an apocalyptic number.

81138379 is a deficient number, since it is larger than the sum of its proper divisors (16471861).

81138379 is a wasteful number, since it uses less digits than its factorization.

81138379 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 610089.

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

The square root of 81138379 is about 9007.6844416309. The cubic root of 81138379 is about 432.9211223388.

The spelling of 81138379 in words is "eighty-one million, one hundred thirty-eight thousand, three hundred seventy-nine".