21529216 has 16 divisors (see below), whose sum is σ = 42890490. Its totient is φ = 10764544.

The previous prime is 21529201. The next prime is 21529217. The reversal of 21529216 is 61292512.

It can be written as a sum of positive squares in only one way, i.e., 15178816 + 6350400 = 3896^2 + 2520^2 .

It is a tau number, because it is divible by the number of its divisors (16).

It is not an unprimeable number, because it can be changed into a prime (21529217) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 83971 + ... + 84226.

Almost surely, 2^21529216 is an apocalyptic number.

It is an amenable number.

21529216 is a deficient number, since it is larger than the sum of its proper divisors (21361274).

21529216 is an equidigital number, since it uses as much as digits as its factorization.

21529216 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 168211 (or 168199 counting only the distinct ones).

The product of its digits is 2160, while the sum is 28.

The square root of 21529216 is about 4639.9586205051. The cubic root of 21529216 is about 278.1907839341.

The spelling of 21529216 in words is "twenty-one million, five hundred twenty-nine thousand, two hundred sixteen".