87221 has 2 divisors, whose sum is σ = 87222. Its totient is φ = 87220.
The previous prime is 87211. The next prime is 87223. The reversal of 87221 is 12278.
It is a strong prime.
It can be written as a sum of positive squares in only one way, i.e., 87025 + 196 = 295^2 + 14^2 .
It is a cyclic number.
It is not a de Polignac number, because 87221 - 210 = 86197 is a prime.
It is a Sophie Germain prime.
Together with 87223, it forms a pair of twin primes.
It is a Chen prime.
It is a Curzon number.
It is a nialpdrome in base 10.
It is a junction number, because it is equal to n+sod(n) for n = 87193 and 87202.
It is a congruent number.
It is not a weakly prime, because it can be changed into another prime (87223) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 43610 + 43611.
It is an arithmetic number, because the mean of its divisors is an integer number (43611).
287221 is an apocalyptic number.
It is an amenable number.
87221 is a deficient number, since it is larger than the sum of its proper divisors (1).
87221 is an equidigital number, since it uses as much as digits as its factorization.
87221 is an odious number, because the sum of its binary digits is odd.
The product of its digits is 224, while the sum is 20.
The square root of 87221 is about 295.3320165509. The cubic root of 87221 is about 44.3479640909.
Adding to 87221 its reverse (12278), we get a palindrome (99499).
The spelling of 87221 in words is "eighty-seven thousand, two hundred twenty-one".
• e-mail: info -at- numbersaplenty.com • Privacy notice • done in 0.129 sec. • engine limits •