81180257 has 8 divisors (see below), whose sum is σ = 84143400. Its totient is φ = 78257664.

The previous prime is 81180241. The next prime is 81180263. The reversal of 81180257 is 75208118.

It is a happy number.

It can be written as a sum of positive squares in 4 ways, for example, as 53816896 + 27363361 = 7336^2 + 5231^2 .

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

It is not a de Polignac number, because 81180257 - 2⁴ = 81180241 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (81180277) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 6032 + ... + 14097.

It is an arithmetic number, because the mean of its divisors is an integer number (10517925).

Almost surely, 2^81180257 is an apocalyptic number.

It is an amenable number.

81180257 is a deficient number, since it is larger than the sum of its proper divisors (2963143).

81180257 is a wasteful number, since it uses less digits than its factorization.

81180257 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 20275.

The product of its (nonzero) digits is 4480, while the sum is 32.

The square root of 81180257 is about 9010.0087125374. The cubic root of 81180257 is about 432.9955908075.

The spelling of 81180257 in words is "eighty-one million, one hundred eighty thousand, two hundred fifty-seven".