81539100 has 54 divisors (see below), whose sum is σ = 255582600. Its totient is φ = 21743520.

The previous prime is 81539099. The next prime is 81539141. The reversal of 81539100 is 193518.

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 17 ways as a sum of consecutive naturals, for example, 44400 + ... + 46199.

Almost surely, 2^81539100 is an apocalyptic number.

It is an amenable number.

81539100 is an abundant number, since it is smaller than the sum of its proper divisors (174043500).

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

81539100 is a wasteful number, since it uses less digits than its factorization.

81539100 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 90619 (or 90609 counting only the distinct ones).

The product of its (nonzero) digits is 1080, while the sum is 27.

The square root of 81539100 is about 9029.9003316759. The cubic root of 81539100 is about 433.6326465958.

The spelling of 81539100 in words is "eighty-one million, five hundred thirty-nine thousand, one hundred".