81547257 has 16 divisors (see below), whose sum is σ = 118784448. Its totient is φ = 49351680.

The previous prime is 81547243. The next prime is 81547273. The reversal of 81547257 is 75274518.

It is not a de Polignac number, because 81547257 - 2¹⁴ = 81530873 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81547357) 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 15 ways as a sum of consecutive naturals, for example, 30153 + ... + 32745.

It is an arithmetic number, because the mean of its divisors is an integer number (7424028).

Almost surely, 2^81547257 is an apocalyptic number.

It is an amenable number.

81547257 is a deficient number, since it is larger than the sum of its proper divisors (37237191).

81547257 is a wasteful number, since it uses less digits than its factorization.

81547257 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3560.

The product of its digits is 78400, while the sum is 39.

The square root of 81547257 is about 9030.3519864953. The cubic root of 81547257 is about 433.6471060128.

The spelling of 81547257 in words is "eighty-one million, five hundred forty-seven thousand, two hundred fifty-seven".