81207770812 has 24 divisors (see below), whose sum is σ = 169477088256. Its totient is φ = 33290141808.

The previous prime is 81207770783. The next prime is 81207770821. The reversal of 81207770812 is 21807770218.

It is a congruent number.

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, 63048868 + ... + 63050155.

It is an arithmetic number, because the mean of its divisors is an integer number (7061545344).

Almost surely, 2^81207770812 is an apocalyptic number.

It is an amenable number.

81207770812 is an abundant number, since it is smaller than the sum of its proper divisors (88269317444).

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

81207770812 is a wasteful number, since it uses less digits than its factorization.

81207770812 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 126099057 (or 126099055 counting only the distinct ones).

The product of its (nonzero) digits is 87808, while the sum is 43.

The spelling of 81207770812 in words is "eighty-one billion, two hundred seven million, seven hundred seventy thousand, eight hundred twelve".