81207257 has 8 divisors (see below), whose sum is σ = 82083456. Its totient is φ = 80336032.

The previous prime is 81207241. The next prime is 81207271. The reversal of 81207257 is 75270218.

It is a sphenic number, since it is the product of 3 distinct primes.

It is a cyclic number.

It is not a de Polignac number, because 81207257 - 2⁴ = 81207241 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81207857) 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 7 ways as a sum of consecutive naturals, for example, 37868 + ... + 39954.

It is an arithmetic number, because the mean of its divisors is an integer number (10260432).

Almost surely, 2^81207257 is an apocalyptic number.

It is an amenable number.

81207257 is a deficient number, since it is larger than the sum of its proper divisors (876199).

81207257 is a wasteful number, since it uses less digits than its factorization.

81207257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2487.

The product of its (nonzero) digits is 7840, while the sum is 32.

The square root of 81207257 is about 9011.5069217085. The cubic root of 81207257 is about 433.0435892804.

The spelling of 81207257 in words is "eighty-one million, two hundred seven thousand, two hundred fifty-seven".