21255529 has 2 divisors, whose sum is σ = 21255530. Its totient is φ = 21255528.

The previous prime is 21255497. The next prime is 21255541. The reversal of 21255529 is 92555212.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 17413929 + 3841600 = 4173^2 + 1960^2 .

It is a cyclic number.

It is not a de Polignac number, because 21255529 - 2⁵ = 21255497 is a prime.

It is a plaindrome in base 16.

It is a self number, because there is not a number n which added to its sum of digits gives 21255529.

It is not a weakly prime, because it can be changed into another prime (21255569) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10627764 + 10627765.

It is an arithmetic number, because the mean of its divisors is an integer number (10627765).

Almost surely, 2^21255529 is an apocalyptic number.

It is an amenable number.

21255529 is a deficient number, since it is larger than the sum of its proper divisors (1).

21255529 is an equidigital number, since it uses as much as digits as its factorization.

21255529 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 9000, while the sum is 31.

The square root of 21255529 is about 4610.3718938932. The cubic root of 21255529 is about 277.0069333197.

The spelling of 21255529 in words is "twenty-one million, two hundred fifty-five thousand, five hundred twenty-nine".