81542880 has 144 divisors (see below), whose sum is σ = 294722064. Its totient is φ = 20459520.

The previous prime is 81542873. The next prime is 81542893. The reversal of 81542880 is 8824518.

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 congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 23 ways as a sum of consecutive naturals, for example, 22815 + ... + 26145.

It is an arithmetic number, because the mean of its divisors is an integer number (2046681).

Almost surely, 2^81542880 is an apocalyptic number.

81542880 is a gapful number since it is divisible by the number (80) 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 81542880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (147361032).

81542880 is an abundant number, since it is smaller than the sum of its proper divisors (213179184).

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

81542880 is a wasteful number, since it uses less digits than its factorization.

81542880 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3369 (or 3358 counting only the distinct ones).

The product of its (nonzero) digits is 20480, while the sum is 36.

The square root of 81542880 is about 9030.1096338860. The cubic root of 81542880 is about 433.6393472914.

The spelling of 81542880 in words is "eighty-one million, five hundred forty-two thousand, eight hundred eighty".