81909511376 has 40 divisors (see below), whose sum is σ = 197859342144. Its totient is φ = 31912796160.

The previous prime is 81909511357. The next prime is 81909511379. The reversal of 81909511376 is 67311590918.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81909511379) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 33241265 + ... + 33243728.

Almost surely, 2^81909511376 is an apocalyptic number.

It is an amenable number.

81909511376 is an abundant number, since it is smaller than the sum of its proper divisors (115949830768).

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

81909511376 is a wasteful number, since it uses less digits than its factorization.

81909511376 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 66485019 (or 66485013 counting only the distinct ones).

The product of its (nonzero) digits is 408240, while the sum is 50.

The spelling of 81909511376 in words is "eighty-one billion, nine hundred nine million, five hundred eleven thousand, three hundred seventy-six".