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BaseRepresentation
bin10011110001101001
311010010001
4103301221
510043001
61423001
7455104
oct236151
9133101
1081001
1155948
123aa61
132ab3b
142173b
1519001
hex13c69

81001 has 2 divisors, whose sum is σ = 81002. Its totient is φ = 81000.

The previous prime is 80989. The next prime is 81013. The reversal of 81001 is 10018.

It is a balanced prime because it is at equal distance from previous prime (80989) and next prime (81013).

It can be written as a sum of positive squares in only one way, i.e., 78400 + 2601 = 280^2 + 51^2 .

It is a cyclic number.

It is not a de Polignac number, because 81001 - 29 = 80489 is a prime.

It is a super-2 number, since 2×810012 = 13122324002, which contains 22 as substring.

81001 is a lucky number.

It is not a weakly prime, because it can be changed into another prime (81031) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40500 + 40501.

It is an arithmetic number, because the mean of its divisors is an integer number (40501).

281001 is an apocalyptic number.

It is an amenable number.

81001 is a deficient number, since it is larger than the sum of its proper divisors (1).

81001 is an equidigital number, since it uses as much as digits as its factorization.

81001 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 8, while the sum is 10.

The square root of 81001 is about 284.6067462307. The cubic root of 81001 is about 43.2676651640.

Adding to 81001 its reverse (10018), we get a palindrome (91019).

It can be divided in two parts, 8 and 1001, that multiplied together give a palindrome (8008).

The spelling of 81001 in words is "eighty-one thousand, one".