81635445168 has 20 divisors (see below), whose sum is σ = 210891566808. Its totient is φ = 27211815040.

The previous prime is 81635445139. The next prime is 81635445169. The reversal of 81635445168 is 86154453618.

It is a happy number.

It is a self number, because there is not a number n which added to its sum of digits gives 81635445168.

It is not an unprimeable number, because it can be changed into a prime (81635445169) 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, 850369173 + ... + 850369268.

Almost surely, 2^81635445168 is an apocalyptic number.

It is an amenable number.

81635445168 is an abundant number, since it is smaller than the sum of its proper divisors (129256121640).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81635445168 is a wasteful number, since it uses less digits than its factorization.

81635445168 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1700738452 (or 1700738446 counting only the distinct ones).

The product of its digits is 2764800, while the sum is 51.

The spelling of 81635445168 in words is "eighty-one billion, six hundred thirty-five million, four hundred forty-five thousand, one hundred sixty-eight".