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81520 = 2451019
BaseRepresentation
bin10011111001110000
311010211021
4103321300
510102040
61425224
7456445
oct237160
9133737
1081520
115627a
123b214
132b14a
14219cc
151924a
hex13e70

81520 has 20 divisors (see below), whose sum is σ = 189720. Its totient is φ = 32576.

The previous prime is 81517. The next prime is 81527. The reversal of 81520 is 2518.

It is a happy number.

It is a tau number, because it is divible by the number of its divisors (20).

It is a Harshad number since it is a multiple of its sum of digits (16).

It is a junction number, because it is equal to n+sod(n) for n = 81494 and 81503.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (81527) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 430 + ... + 589.

It is an arithmetic number, because the mean of its divisors is an integer number (9486).

281520 is an apocalyptic number.

81520 is a gapful number since it is divisible by the number (80) formed by its first and last digit.

It is an amenable number.

81520 is an abundant number, since it is smaller than the sum of its proper divisors (108200).

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

It is a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (94860).

81520 is a wasteful number, since it uses less digits than its factorization.

81520 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1032 (or 1026 counting only the distinct ones).

The product of its (nonzero) digits is 80, while the sum is 16.

The square root of 81520 is about 285.5170747959. The cubic root of 81520 is about 43.3598785416.

The spelling of 81520 in words is "eighty-one thousand, five hundred twenty".

Divisors: 1 2 4 5 8 10 16 20 40 80 1019 2038 4076 5095 8152 10190 16304 20380 40760 81520