81115391930578 has 4 divisors (see below), whose sum is σ = 121673087895870. Its totient is φ = 40557695965288.

The previous prime is 81115391930477. The next prime is 81115391930581. The reversal of 81115391930578 is 87503919351118.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in only one way, i.e., 77351725970289 + 3763665960289 = 8794983^2 + 1940017^2 .

It is an unprimeable number.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 20278847982643 + ... + 20278847982646.

Almost surely, 2^{81115391930578} is an apocalyptic number.

81115391930578 is a deficient number, since it is larger than the sum of its proper divisors (40557695965292).

81115391930578 is a wasteful number, since it uses less digits than its factorization.

81115391930578 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 40557695965291.

The product of its (nonzero) digits is 8164800, while the sum is 61.

The spelling of 81115391930578 in words is "eighty-one trillion, one hundred fifteen billion, three hundred ninety-one million, nine hundred thirty thousand, five hundred seventy-eight".