21529 has 2 divisors, whose sum is σ = 21530.
Its totient is φ = 21528.
The previous prime is 21523. The next prime is 21557. The reversal of 21529 is 92512.
It is a weak prime.
It can be written as a sum of positive squares in only one way, i.e., 15129 + 6400 = 123^2 + 80^2
It is a cyclic number.
It is not a de Polignac number, because 21529 - 23 = 21521 is a prime.
It is a Chen prime.
It is a pancake number, because a pancake can be divided into 21529 parts by 207 straight cuts.
21529 is a lucky number.
It is a plaindrome in base 14.
It is not a weakly prime, because it can be changed into another prime (21521) by changing a digit.
It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10764 + 10765.
It is an arithmetic number, because the mean of its divisors is an integer number (10765).
221529 is an apocalyptic number.
It is an amenable number.
21529 is a deficient number, since it is larger than the sum of its proper divisors (1).
21529 is an equidigital number, since it uses as much as digits as its factorization.
21529 is an evil number, because the sum of its binary digits is even.
The product of its digits is 180, while the sum is 19.
The square root of 21529 is about 146.7276388415.
The cubic root of 21529 is about 27.8189853580.
The spelling of 21529 in words is "twenty-one thousand, five hundred twenty-nine".