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72581 = 181401

72581 has 4 divisors (see below), whose sum is σ = 73164. Its totient is φ = 72000.

The previous prime is 72577. The next prime is 72613. The reversal of 72581 is 18527.

72581 = 1902 + 1912.

It is a semiprime because it is the product of two primes, and also a brilliant number, because the two primes have the same length, and also an emirpimes, since its reverse is a distinct semiprime: 18527 = 97191.

It can be written as a sum of positive squares in 2 ways, for example, as 36481 + 36100 = 191^2 + 190^2 .

It is a cyclic number.

It is not a de Polignac number, because 72581 - 22 = 72577 is a prime.

It is a super-2 number, since 2×725812 = 10536003122, which contains 22 as substring.

It is an Ulam number.

It is an alternating number because its digits alternate between odd and even.

It is a Duffinian number.

It is a plaindrome in base 15.

It is a congruent number.

It is an inconsummate number, since it does not exist a number n which divided by its sum of digits gives 72581.

It is not an unprimeable number, because it can be changed into a prime (72551) 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, 20 + ... + 381.

It is an arithmetic number, because the mean of its divisors is an integer number (18291).

272581 is an apocalyptic number.

72581 is the 191-st centered square number.

It is an amenable number.

72581 is a deficient number, since it is larger than the sum of its proper divisors (583).

72581 is a wasteful number, since it uses less digits than its factorization.

72581 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 582.

The product of its digits is 560, while the sum is 23.

The square root of 72581 is about 269.4086115921. The cubic root of 72581 is about 41.7132776164.

The spelling of 72581 in words is "seventy-two thousand, five hundred eighty-one".

Divisors: 1 181 401 72581