81071780665 has 8 divisors (see below), whose sum is σ = 97289898048. Its totient is φ = 64854917040.

The previous prime is 81071780627. The next prime is 81071780677. The reversal of 81071780665 is 56608717018.

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

It is a de Polignac number, because none of the positive numbers 2^k-81071780665 is a prime.

It is a super-3 number, since 3×81071780665³ (a number of 34 digits) contains 333 as substring.

It is a Duffinian number.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 164767 + ... + 435076.

It is an arithmetic number, because the mean of its divisors is an integer number (12161237256).

Almost surely, 2^81071780665 is an apocalyptic number.

It is an amenable number.

81071780665 is a deficient number, since it is larger than the sum of its proper divisors (16218117383).

81071780665 is a wasteful number, since it uses less digits than its factorization.

81071780665 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 626879.

The product of its (nonzero) digits is 564480, while the sum is 49.

The spelling of 81071780665 in words is "eighty-one billion, seventy-one million, seven hundred eighty thousand, six hundred sixty-five".