81535972768 has 24 divisors (see below), whose sum is σ = 160536448800. Its totient is φ = 40764811200.

The previous prime is 81535972729. The next prime is 81535972789. The reversal of 81535972768 is 86727953518.

It is a super-2 number, since 2×81535972768² (a number of 23 digits) contains 22 as substring.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 349243 + ... + 533893.

It is an arithmetic number, because the mean of its divisors is an integer number (6689018700).

Almost surely, 2^81535972768 is an apocalyptic number.

It is an amenable number.

81535972768 is a deficient number, since it is larger than the sum of its proper divisors (79000476032).

81535972768 is a wasteful number, since it uses less digits than its factorization.

81535972768 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 198460 (or 198452 counting only the distinct ones).

The product of its digits is 25401600, while the sum is 61.

The spelling of 81535972768 in words is "eighty-one billion, five hundred thirty-five million, nine hundred seventy-two thousand, seven hundred sixty-eight".