81791203565 has 8 divisors (see below), whose sum is σ = 99102352128. Its totient is φ = 64797690960.

The previous prime is 81791203561. The next prime is 81791203603. The reversal of 81791203565 is 56530219718.

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

It is not a de Polignac number, because 81791203565 - 2² = 81791203561 is a prime.

It is a super-2 number, since 2×81791203565² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81791203561) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 79408421 + ... + 79409450.

It is an arithmetic number, because the mean of its divisors is an integer number (12387794016).

Almost surely, 2^81791203565 is an apocalyptic number.

It is an amenable number.

81791203565 is a deficient number, since it is larger than the sum of its proper divisors (17311148563).

81791203565 is a wasteful number, since it uses less digits than its factorization.

81791203565 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 158817979.

The product of its (nonzero) digits is 453600, while the sum is 47.

The spelling of 81791203565 in words is "eighty-one billion, seven hundred ninety-one million, two hundred three thousand, five hundred sixty-five".