81578464 has 48 divisors (see below), whose sum is σ = 178972416. Its totient is φ = 36284800.

The previous prime is 81578423. The next prime is 81578467. The reversal of 81578464 is 46487518.

It is a self number, because there is not a number n which added to its sum of digits gives 81578464.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81578467) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 14079 + ... + 19009.

It is an arithmetic number, because the mean of its divisors is an integer number (3728592).

Almost surely, 2^81578464 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 81578464, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (89486208).

81578464 is an abundant number, since it is smaller than the sum of its proper divisors (97393952).

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

81578464 is a wasteful number, since it uses less digits than its factorization.

81578464 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4999 (or 4991 counting only the distinct ones).

The product of its digits is 215040, while the sum is 43.

The square root of 81578464 is about 9032.0797162115. The cubic root of 81578464 is about 433.7024158615.

The spelling of 81578464 in words is "eighty-one million, five hundred seventy-eight thousand, four hundred sixty-four".