81917628512 has 24 divisors (see below), whose sum is σ = 161870460192. Its totient is φ = 40807670400.

The previous prime is 81917628509. The next prime is 81917628517. The reversal of 81917628512 is 21582671918.

It is a super-2 number, since 2×81917628512² (a number of 23 digits) contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81917628517) 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, 4714439 + ... + 4731782.

It is an arithmetic number, because the mean of its divisors is an integer number (6744602508).

Almost surely, 2^81917628512 is an apocalyptic number.

It is an amenable number.

81917628512 is a deficient number, since it is larger than the sum of its proper divisors (79952831680).

81917628512 is a wasteful number, since it uses less digits than its factorization.

81917628512 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 9446502 (or 9446494 counting only the distinct ones).

The product of its digits is 483840, while the sum is 50.

The spelling of 81917628512 in words is "eighty-one billion, nine hundred seventeen million, six hundred twenty-eight thousand, five hundred twelve".