21328529 has 4 divisors (see below), whose sum is σ = 21341760. Its totient is φ = 21315300.

The previous prime is 21328501. The next prime is 21328537. The reversal of 21328529 is 92582312.

It is a happy number.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21328529 - 2⁸ = 21328273 is a prime.

It is a super-2 number, since 2×21328529² = 909812298607682, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 21328495 and 21328504.

It is not an unprimeable number, because it can be changed into a prime (21328729) 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 in 3 ways as a sum of consecutive naturals, for example, 3797 + ... + 7554.

It is an arithmetic number, because the mean of its divisors is an integer number (5335440).

Almost surely, 2^21328529 is an apocalyptic number.

It is an amenable number.

21328529 is a deficient number, since it is larger than the sum of its proper divisors (13231).

21328529 is a wasteful number, since it uses less digits than its factorization.

21328529 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 13230.

The product of its digits is 8640, while the sum is 32.

The square root of 21328529 is about 4618.2820398932. The cubic root of 21328529 is about 277.3236885604.

The spelling of 21328529 in words is "twenty-one million, three hundred twenty-eight thousand, five hundred twenty-nine".