81544257 has 24 divisors (see below), whose sum is σ = 131283360. Its totient is φ = 48470400.

The previous prime is 81544247. The next prime is 81544261. The reversal of 81544257 is 75244518.

It is not a de Polignac number, because 81544257 - 2⁶ = 81544193 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81544247) by changing a digit.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 11119 + ... + 16932.

It is an arithmetic number, because the mean of its divisors is an integer number (5470140).

Almost surely, 2^81544257 is an apocalyptic number.

It is an amenable number.

81544257 is a deficient number, since it is larger than the sum of its proper divisors (49739103).

81544257 is a wasteful number, since it uses less digits than its factorization.

81544257 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 28093 (or 28090 counting only the distinct ones).

The product of its digits is 44800, while the sum is 36.

The square root of 81544257 is about 9030.1858784856. The cubic root of 81544257 is about 433.6417882077.

The spelling of 81544257 in words is "eighty-one million, five hundred forty-four thousand, two hundred fifty-seven".