81908645392 has 120 divisors (see below), whose sum is σ = 195039480960. Its totient is φ = 33171667200.

The previous prime is 81908645381. The next prime is 81908645411. The reversal of 81908645392 is 29354680918.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 1030267 + ... + 1106917.

It is an arithmetic number, because the mean of its divisors is an integer number (1625329008).

Almost surely, 2^81908645392 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81908645392, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (97519740480).

81908645392 is an abundant number, since it is smaller than the sum of its proper divisors (113130835568).

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

81908645392 is a wasteful number, since it uses less digits than its factorization.

81908645392 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 76749 (or 76736 counting only the distinct ones).

The product of its (nonzero) digits is 3732480, while the sum is 55.

The spelling of 81908645392 in words is "eighty-one billion, nine hundred eight million, six hundred forty-five thousand, three hundred ninety-two".