81905898240 has 108 divisors (see below), whose sum is σ = 283385915904. Its totient is φ = 21841569792.

The previous prime is 81905898203. The next prime is 81905898293. The reversal of 81905898240 is 4289850918.

81905898240 is a `hidden beast` number, since 8 + 19 + 0 + 589 + 8 + 2 + 40 = 666.

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 3543424 + ... + 3566463.

Almost surely, 2^81905898240 is an apocalyptic number.

81905898240 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81905898240 is an abundant number, since it is smaller than the sum of its proper divisors (201480017664).

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

81905898240 is a wasteful number, since it uses less digits than its factorization.

81905898240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7109914 (or 7109897 counting only the distinct ones).

The product of its (nonzero) digits is 1658880, while the sum is 54.

The spelling of 81905898240 in words is "eighty-one billion, nine hundred five million, eight hundred ninety-eight thousand, two hundred forty".