81651198752 has 48 divisors (see below), whose sum is σ = 161121155832. Its totient is φ = 40731678720.

The previous prime is 81651198743. The next prime is 81651198779. The reversal of 81651198752 is 25789115618.

It can be written as a sum of positive squares in 4 ways, for example, as 35252315536 + 46398883216 = 187756^2 + 215404^2 .

It is a junction number, because it is equal to n+sod(n) for n = 81651198694 and 81651198703.

It is an unprimeable number.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 37923308 + ... + 37925460.

Almost surely, 2^81651198752 is an apocalyptic number.

It is an amenable number.

81651198752 is a deficient number, since it is larger than the sum of its proper divisors (79469957080).

81651198752 is a wasteful number, since it uses less digits than its factorization.

81651198752 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4341 (or 4333 counting only the distinct ones).

The product of its digits is 1209600, while the sum is 53.

The spelling of 81651198752 in words is "eighty-one billion, six hundred fifty-one million, one hundred ninety-eight thousand, seven hundred fifty-two".