81534549 has 4 divisors (see below), whose sum is σ = 108712736. Its totient is φ = 54356364.

The previous prime is 81534487. The next prime is 81534553. The reversal of 81534549 is 94543518.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is not a de Polignac number, because 81534549 - 2¹⁹ = 81010261 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81534449) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 13589089 + ... + 13589094.

It is an arithmetic number, because the mean of its divisors is an integer number (27178184).

Almost surely, 2^81534549 is an apocalyptic number.

It is an amenable number.

81534549 is a deficient number, since it is larger than the sum of its proper divisors (27178187).

81534549 is a wasteful number, since it uses less digits than its factorization.

81534549 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 27178186.

The product of its digits is 86400, while the sum is 39.

The square root of 81534549 is about 9029.6483320227. The cubic root of 81534549 is about 433.6245788962.

The spelling of 81534549 in words is "eighty-one million, five hundred thirty-four thousand, five hundred forty-nine".