81045549 has 32 divisors (see below), whose sum is σ = 131116160. Its totient is φ = 49175424.

The previous prime is 81045529. The next prime is 81045557. The reversal of 81045549 is 94554018.

81045549 is a `hidden beast` number, since 8 + 104 + 5 + 549 = 666.

It is not a de Polignac number, because 81045549 - 2⁹ = 81045037 is a prime.

It is a super-2 number, since 2×81045549² = 13136762025422802, which contains 22 as substring.

It is a Smith number, since the sum of its digits (36) coincides with the sum of the digits of its prime factors.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81045529) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 24042 + ... + 27204.

It is an arithmetic number, because the mean of its divisors is an integer number (4097380).

Almost surely, 2^81045549 is an apocalyptic number.

81045549 is the 5694-th heptagonal number.

It is an amenable number.

81045549 is a deficient number, since it is larger than the sum of its proper divisors (50070611).

81045549 is a wasteful number, since it uses less digits than its factorization.

81045549 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3258 (or 3252 counting only the distinct ones).

The product of its (nonzero) digits is 28800, while the sum is 36.

The square root of 81045549 is about 9002.5301443539. The cubic root of 81045549 is about 432.7559583956.

The spelling of 81045549 in words is "eighty-one million, forty-five thousand, five hundred forty-nine".