21529217 has 2 divisors, whose sum is σ = 21529218. Its totient is φ = 21529216.

The previous prime is 21529201. The next prime is 21529229. The reversal of 21529217 is 71292512.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 16516096 + 5013121 = 4064^2 + 2239^2 .

It is a cyclic number.

It is not a de Polignac number, because 21529217 - 2⁴ = 21529201 is a prime.

It is a Chen prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21529217.

It is not a weakly prime, because it can be changed into another prime (21529237) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (7) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10764608 + 10764609.

It is an arithmetic number, because the mean of its divisors is an integer number (10764609).

Almost surely, 2^21529217 is an apocalyptic number.

It is an amenable number.

21529217 is a deficient number, since it is larger than the sum of its proper divisors (1).

21529217 is an equidigital number, since it uses as much as digits as its factorization.

21529217 is an odious number, because the sum of its binary digits is odd.

The product of its digits is 2520, while the sum is 29.

The square root of 21529217 is about 4639.9587282647. The cubic root of 21529217 is about 278.1907882413.

The spelling of 21529217 in words is "twenty-one million, five hundred twenty-nine thousand, two hundred seventeen".