81165240 has 320 divisors, whose sum is σ = 307359360. Its totient is φ = 19077120.

The previous prime is 81165221. The next prime is 81165251. The reversal of 81165240 is 4256118.

81165240 is a `hidden beast` number, since 8 + 1 + 1 + 652 + 4 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 1726897 + ... + 1726943.

It is an arithmetic number, because the mean of its divisors is an integer number (960498).

Almost surely, 2^81165240 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81165240, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (153679680).

81165240 is an abundant number, since it is smaller than the sum of its proper divisors (226194120).

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

81165240 is a wasteful number, since it uses less digits than its factorization.

81165240 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 124 (or 111 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 27.

The square root of 81165240 is about 9009.1753229694. The cubic root of 81165240 is about 432.9688901621.

The spelling of 81165240 in words is "eighty-one million, one hundred sixty-five thousand, two hundred forty".