81887520 has 192 divisors, whose sum is σ = 303295104. Its totient is φ = 18309120.

The previous prime is 81887513. The next prime is 81887527. The reversal of 81887520 is 2578818.

It is an interprime number because it is at equal distance from previous prime (81887513) and next prime (81887527).

It is a Harshad number since it is a multiple of its sum of digits (39).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81887527) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 68044 + ... + 69236.

It is an arithmetic number, because the mean of its divisors is an integer number (1579662).

Almost surely, 2^81887520 is an apocalyptic number.

81887520 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 81887520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (151647552).

81887520 is an abundant number, since it is smaller than the sum of its proper divisors (221407584).

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

81887520 is a wasteful number, since it uses less digits than its factorization.

81887520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1235 (or 1227 counting only the distinct ones).

The product of its (nonzero) digits is 35840, while the sum is 39.

The square root of 81887520 is about 9049.1723378439. The cubic root of 81887520 is about 434.2494124451.

The spelling of 81887520 in words is "eighty-one million, eight hundred eighty-seven thousand, five hundred twenty".