81750009 has 32 divisors (see below), whose sum is σ = 124084224. Its totient is φ = 47436480.

The previous prime is 81749977. The next prime is 81750013. The reversal of 81750009 is 90005718.

It is not a de Polignac number, because 81750009 - 2⁵ = 81749977 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81750089) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 74664 + ... + 75750.

It is an arithmetic number, because the mean of its divisors is an integer number (3877632).

Almost surely, 2^81750009 is an apocalyptic number.

It is an amenable number.

81750009 is a deficient number, since it is larger than the sum of its proper divisors (42334215).

81750009 is a wasteful number, since it uses less digits than its factorization.

81750009 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1197.

The product of its (nonzero) digits is 2520, while the sum is 30.

The square root of 81750009 is about 9041.5711577137. The cubic root of 81750009 is about 434.0062027046.

The spelling of 81750009 in words is "eighty-one million, seven hundred fifty thousand, nine".