81817606646 has 16 divisors (see below), whose sum is σ = 123615925200. Its totient is φ = 40612591200.

The previous prime is 81817606643. The next prime is 81817606667. The reversal of 81817606646 is 64660671818.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81817606643) 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, 494285 + ... + 638711.

It is an arithmetic number, because the mean of its divisors is an integer number (7725995325).

Almost surely, 2^81817606646 is an apocalyptic number.

81817606646 is a deficient number, since it is larger than the sum of its proper divisors (41798318554).

81817606646 is a wasteful number, since it uses less digits than its factorization.

81817606646 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 146479.

The product of its (nonzero) digits is 2322432, while the sum is 53.

The spelling of 81817606646 in words is "eighty-one billion, eight hundred seventeen million, six hundred six thousand, six hundred forty-six".