21028569 has 8 divisors (see below), whose sum is σ = 28069920. Its totient is φ = 14003136.

The previous prime is 21028549. The next prime is 21028597. The reversal of 21028569 is 96582012.

It is a sphenic number, since it is the product of 3 distinct primes.

It is not a de Polignac number, because 21028569 - 2¹⁷ = 20897497 is a prime.

It is a super-2 number, since 2×21028569² = 884401428375522, which contains 22 as substring.

It is not an unprimeable number, because it can be changed into a prime (21028549) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 447 + ... + 6500.

It is an arithmetic number, because the mean of its divisors is an integer number (3508740).

Almost surely, 2^21028569 is an apocalyptic number.

It is an amenable number.

21028569 is a deficient number, since it is larger than the sum of its proper divisors (7041351).

21028569 is a wasteful number, since it uses less digits than its factorization.

21028569 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7959.

The product of its (nonzero) digits is 8640, while the sum is 33.

The square root of 21028569 is about 4585.6917689701. The cubic root of 21028569 is about 276.0174715888.

The spelling of 21028569 in words is "twenty-one million, twenty-eight thousand, five hundred sixty-nine".