81013 has 2 divisors, whose sum is σ = 81014. Its totient is φ = 81012.
The previous prime is 81001. The next prime is 81017. The reversal of 81013 is 31018.
It is a strong prime.
It can be written as a sum of positive squares in only one way, i.e., 47524 + 33489 = 218^2 + 183^2 .
It is a cyclic number.
It is a de Polignac number, because none of the positive numbers 2k-81013 is a prime.
It is a junction number, because it is equal to n+sod(n) for n = 80984 and 81002.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (81017) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 40506 + 40507.
It is an arithmetic number, because the mean of its divisors is an integer number (40507).
281013 is an apocalyptic number.
It is an amenable number.
81013 is a deficient number, since it is larger than the sum of its proper divisors (1).
81013 is an equidigital number, since it uses as much as digits as its factorization.
81013 is an evil number, because the sum of its binary digits is even.
The product of its (nonzero) digits is 24, while the sum is 13.
The square root of 81013 is about 284.6278271709. The cubic root of 81013 is about 43.2698017069.
The spelling of 81013 in words is "eighty-one thousand, thirteen".
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