81509760 has 256 divisors, whose sum is σ = 297432000. Its totient is φ = 21086208.

The previous prime is 81509759. The next prime is 81509783. The reversal of 81509760 is 6790518.

81509760 is a `hidden beast` number, since 81 + 509 + 76 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 915796 + ... + 915884.

Almost surely, 2^81509760 is an apocalyptic number.

81509760 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81509760, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (148716000).

81509760 is an abundant number, since it is smaller than the sum of its proper divisors (215922240).

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

81509760 is a wasteful number, since it uses less digits than its factorization.

81509760 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 170 (or 152 counting only the distinct ones).

The product of its (nonzero) digits is 15120, while the sum is 36.

The square root of 81509760 is about 9028.2755828563. The cubic root of 81509760 is about 433.5806293911.

The spelling of 81509760 in words is "eighty-one million, five hundred nine thousand, seven hundred sixty".