81316894787 has 16 divisors (see below), whose sum is σ = 81972552960. Its totient is φ = 80665015200.

The previous prime is 81316894783. The next prime is 81316894793. The reversal of 81316894787 is 78749861318.

It is not a de Polignac number, because 81316894787 - 2² = 81316894783 is a prime.

It is a super-2 number, since 2×81316894787² (a number of 23 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81316894783) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 82722698 + ... + 82723680.

It is an arithmetic number, because the mean of its divisors is an integer number (5123284560).

Almost surely, 2^81316894787 is an apocalyptic number.

81316894787 is a deficient number, since it is larger than the sum of its proper divisors (655658173).

81316894787 is a wasteful number, since it uses less digits than its factorization.

81316894787 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2314.

The product of its digits is 16257024, while the sum is 62.

The spelling of 81316894787 in words is "eighty-one billion, three hundred sixteen million, eight hundred ninety-four thousand, seven hundred eighty-seven".