81705150 has 72 divisors (see below), whose sum is σ = 226634304. Its totient is φ = 21081600.

The previous prime is 81705133. The next prime is 81705157. The reversal of 81705150 is 5150718.

81705150 is a `hidden beast` number, since 81 + 70 + 515 + 0 = 666.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81705157) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 11022 + ... + 16878.

Almost surely, 2^81705150 is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81705150, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (113317152).

81705150 is an abundant number, since it is smaller than the sum of its proper divisors (144929154).

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

81705150 is a wasteful number, since it uses less digits than its factorization.

81705150 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5906 (or 5898 counting only the distinct ones).

The product of its (nonzero) digits is 1400, while the sum is 27.

The square root of 81705150 is about 9039.0901090762. The cubic root of 81705150 is about 433.9268035434.

Adding to 81705150 its reverse (5150718), we get a palindrome (86855868).

The spelling of 81705150 in words is "eighty-one million, seven hundred five thousand, one hundred fifty".