75721 has 2 divisors, whose sum is σ = 75722. Its totient is φ = 75720.
The previous prime is 75709. The next prime is 75731. The reversal of 75721 is 12757.
75721 is nontrivially palindromic in base 2.
It is a strong prime.
It can be written as a sum of positive squares in only one way, i.e., 40000 + 35721 = 200^2 + 189^2 .
It is an emirp because it is prime and its reverse (12757) is a distict prime.
It is a cyclic number.
It is not a de Polignac number, because 75721 - 25 = 75689 is a prime.
It is a junction number, because it is equal to n+sod(n) for n = 75692 and 75701.
It is not a weakly prime, because it can be changed into another prime (75731) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 37860 + 37861.
It is an arithmetic number, because the mean of its divisors is an integer number (37861).
275721 is an apocalyptic number.
It is an amenable number.
75721 is a deficient number, since it is larger than the sum of its proper divisors (1).
75721 is an equidigital number, since it uses as much as digits as its factorization.
75721 is an odious number, because the sum of its binary digits is odd.
The product of its digits is 490, while the sum is 22.
The square root of 75721 is about 275.1744900967. The cubic root of 75721 is about 42.3063391811.
The spelling of 75721 in words is "seventy-five thousand, seven hundred twenty-one".
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