81544521 has 8 divisors (see below), whose sum is σ = 108849024. Its totient is φ = 54301520.

The previous prime is 81544501. The next prime is 81544579. The reversal of 81544521 is 12544518.

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 81544521 - 2¹¹ = 81542473 is a prime.

It is not an unprimeable number, because it can be changed into a prime (81544501) 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, 12186 + ... + 17651.

It is an arithmetic number, because the mean of its divisors is an integer number (13606128).

Almost surely, 2^81544521 is an apocalyptic number.

It is an amenable number.

81544521 is a deficient number, since it is larger than the sum of its proper divisors (27304503).

81544521 is a wasteful number, since it uses less digits than its factorization.

81544521 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 30751.

The product of its digits is 6400, while the sum is 30.

The square root of 81544521 is about 9030.2004961130. The cubic root of 81544521 is about 433.6422561798.

The spelling of 81544521 in words is "eighty-one million, five hundred forty-four thousand, five hundred twenty-one".