81464544 has 144 divisors (see below), whose sum is σ = 280451808. Its totient is φ = 21897216.

The previous prime is 81464543. The next prime is 81464549. The reversal of 81464544 is 44546418.

It is a happy number.

81464544 is a `hidden beast` number, since 8 + 1 + 4 + 645 + 4 + 4 = 666.

It is a tau number, because it is divible by the number of its divisors (144).

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a junction number, because it is equal to n+sod(n) for n = 81464499 and 81464508.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81464543) 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, 33084 + ... + 35460.

It is an arithmetic number, because the mean of its divisors is an integer number (1947582).

Almost surely, 2^81464544 is an apocalyptic number.

81464544 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 81464544, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (140225904).

81464544 is an abundant number, since it is smaller than the sum of its proper divisors (198987264).

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

81464544 is a wasteful number, since it uses less digits than its factorization.

81464544 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2417 (or 2406 counting only the distinct ones).

The product of its digits is 61440, while the sum is 36.

The square root of 81464544 is about 9025.7711027923. The cubic root of 81464544 is about 433.5004410064.

The spelling of 81464544 in words is "eighty-one million, four hundred sixty-four thousand, five hundred forty-four".