81399138 has 8 divisors (see below), whose sum is σ = 162798288. Its totient is φ = 27133044.

The previous prime is 81399127. The next prime is 81399187. The reversal of 81399138 is 83199318.

It is a happy number.

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

81399138 is an admirable number.

It is a self number, because there is not a number n which added to its sum of digits gives 81399138.

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, 6783256 + ... + 6783267.

It is an arithmetic number, because the mean of its divisors is an integer number (20349786).

Almost surely, 2^81399138 is an apocalyptic number.

81399138 is a primitive abundant number, since it is smaller than the sum of its proper divisors, none of which is abundant.

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

81399138 is a wasteful number, since it uses less digits than its factorization.

81399138 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13566528.

The product of its digits is 46656, while the sum is 42.

The square root of 81399138 is about 9022.1470837046. The cubic root of 81399138 is about 433.3843941146.

The spelling of 81399138 in words is "eighty-one million, three hundred ninety-nine thousand, one hundred thirty-eight".