816440012581 has 8 divisors (see below), whose sum is σ = 873024965784. Its totient is φ = 760806067200.

The previous prime is 816440012551. The next prime is 816440012611. The reversal of 816440012581 is 185210044618.

It is an interprime number because it is at equal distance from previous prime (816440012551) and next prime (816440012611).

It can be written as a sum of positive squares in 4 ways, for example, as 581496228481 + 234943784100 = 762559^2 + 484710^2 .

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

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-816440012581 is a prime.

It is a super-2 number, since 2×816440012581² (a number of 25 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (816440012551) 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, 237750180 + ... + 237753613.

It is an arithmetic number, because the mean of its divisors is an integer number (109128120723).

Almost surely, 2^816440012581 is an apocalyptic number.

It is an amenable number.

816440012581 is a deficient number, since it is larger than the sum of its proper divisors (56584953203).

816440012581 is a wasteful number, since it uses less digits than its factorization.

816440012581 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 475503911.

The product of its (nonzero) digits is 61440, while the sum is 40.

The spelling of 816440012581 in words is "eight hundred sixteen billion, four hundred forty million, twelve thousand, five hundred eighty-one".