81787331005 has 4 divisors (see below), whose sum is σ = 98144797212. Its totient is φ = 65429864800.

The previous prime is 81787330943. The next prime is 81787331023. The reversal of 81787331005 is 50013378718.

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

It can be written as a sum of positive squares in 2 ways, for example, as 17979055396 + 63808275609 = 134086^2 + 252603^2 .

It is not a de Polignac number, because 81787331005 - 2²⁷ = 81653113277 is a prime.

It is a Duffinian number.

It is a congruent 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, 8178733096 + ... + 8178733105.

It is an arithmetic number, because the mean of its divisors is an integer number (24536199303).

Almost surely, 2^81787331005 is an apocalyptic number.

It is an amenable number.

81787331005 is a deficient number, since it is larger than the sum of its proper divisors (16357466207).

81787331005 is a wasteful number, since it uses less digits than its factorization.

81787331005 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 16357466206.

The product of its (nonzero) digits is 141120, while the sum is 43.

The spelling of 81787331005 in words is "eighty-one billion, seven hundred eighty-seven million, three hundred thirty-one thousand, five".