81191738 has 8 divisors (see below), whose sum is σ = 121832640. Its totient is φ = 40580860.

The previous prime is 81191717. The next prime is 81191741. The reversal of 81191738 is 83719118.

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

It is a Curzon 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, 1343 + ... + 12813.

It is an arithmetic number, because the mean of its divisors is an integer number (15229080).

Almost surely, 2^81191738 is an apocalyptic number.

81191738 is a deficient number, since it is larger than the sum of its proper divisors (40640902).

81191738 is a wasteful number, since it uses less digits than its factorization.

81191738 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 15012.

The product of its digits is 12096, while the sum is 38.

The square root of 81191738 is about 9010.6458148126. The cubic root of 81191738 is about 433.0160021252.

The spelling of 81191738 in words is "eighty-one million, one hundred ninety-one thousand, seven hundred thirty-eight".