81640313212 has 12 divisors (see below), whose sum is σ = 143439755256. Its totient is φ = 40657526000.

The previous prime is 81640313207. The next prime is 81640313219. The reversal of 81640313212 is 21231304618.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81640313219) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 40656523 + ... + 40658530.

It is an arithmetic number, because the mean of its divisors is an integer number (11953312938).

Almost surely, 2^81640313212 is an apocalyptic number.

It is an amenable number.

81640313212 is a deficient number, since it is larger than the sum of its proper divisors (61799442044).

81640313212 is a wasteful number, since it uses less digits than its factorization.

81640313212 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 81315308 (or 81315306 counting only the distinct ones).

The product of its (nonzero) digits is 6912, while the sum is 31.

The spelling of 81640313212 in words is "eighty-one billion, six hundred forty million, three hundred thirteen thousand, two hundred twelve".