81549384 has 64 divisors (see below), whose sum is σ = 233754240. Its totient is φ = 23224320.

The previous prime is 81549383. The next prime is 81549397. The reversal of 81549384 is 48394518.

It is a Harshad number since it is a multiple of its sum of digits (42).

It is not an unprimeable number, because it can be changed into a prime (81549383) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 70152 + ... + 71304.

It is an arithmetic number, because the mean of its divisors is an integer number (3652410).

Almost surely, 2^81549384 is an apocalyptic number.

81549384 is a gapful number since it is divisible by the number (84) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81549384, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (116877120).

81549384 is an abundant number, since it is smaller than the sum of its proper divisors (152204856).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

81549384 is a wasteful number, since it uses less digits than its factorization.

81549384 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1590 (or 1586 counting only the distinct ones).

The product of its digits is 138240, while the sum is 42.

The square root of 81549384 is about 9030.4697552231. The cubic root of 81549384 is about 433.6508762577.

The spelling of 81549384 in words is "eighty-one million, five hundred forty-nine thousand, three hundred eighty-four".