81909511374 has 16 divisors (see below), whose sum is σ = 163822402512. Its totient is φ = 27302607168.

The previous prime is 81909511357. The next prime is 81909511379. The reversal of 81909511374 is 47311590918.

It is a Curzon number.

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, 263562 + ... + 482994.

It is an arithmetic number, because the mean of its divisors is an integer number (10238900157).

Almost surely, 2^81909511374 is an apocalyptic number.

81909511374 is an abundant number, since it is smaller than the sum of its proper divisors (81912891138).

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

81909511374 is a wasteful number, since it uses less digits than its factorization.

81909511374 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 281651.

The product of its (nonzero) digits is 272160, while the sum is 48.

The spelling of 81909511374 in words is "eighty-one billion, nine hundred nine million, five hundred eleven thousand, three hundred seventy-four".