81580500 has 96 divisors (see below), whose sum is σ = 264001920. Its totient is φ = 21751200.

The previous prime is 81580489. The next prime is 81580511. The reversal of 81580500 is 508518.

81580500 is a `hidden beast` number, since 8 + 158 + 0 + 500 = 666.

It is an interprime number because it is at equal distance from previous prime (81580489) and next prime (81580511).

It is a Harshad number since it is a multiple of its sum of digits (27).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 10479 + ... + 16521.

It is an arithmetic number, because the mean of its divisors is an integer number (2750020).

Almost surely, 2^81580500 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 81580500, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (132000960).

81580500 is an abundant number, since it is smaller than the sum of its proper divisors (182421420).

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

81580500 is a wasteful number, since it uses less digits than its factorization.

81580500 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 6071 (or 6053 counting only the distinct ones).

The product of its (nonzero) digits is 1600, while the sum is 27.

The square root of 81580500 is about 9032.1924248767. The cubic root of 81580500 is about 433.7060238839.

The spelling of 81580500 in words is "eighty-one million, five hundred eighty thousand, five hundred".