21428569 has 8 divisors (see below), whose sum is σ = 22094208. Its totient is φ = 20771760.

The previous prime is 21428549. The next prime is 21428579. The reversal of 21428569 is 96582412.

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

It is a cyclic number.

It is not a de Polignac number, because 21428569 - 2¹¹ = 21426521 is a prime.

It is a super-2 number, since 2×21428569² = 918367138775522, which contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21428509) by changing a digit.

It is a polite number, since it can be written in 7 ways as a sum of consecutive naturals, for example, 2899 + ... + 7159.

It is an arithmetic number, because the mean of its divisors is an integer number (2761776).

Almost surely, 2^21428569 is an apocalyptic number.

It is an amenable number.

21428569 is a deficient number, since it is larger than the sum of its proper divisors (665639).

21428569 is a wasteful number, since it uses less digits than its factorization.

21428569 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4415.

The product of its digits is 34560, while the sum is 37.

The square root of 21428569 is about 4629.1002365471. The cubic root of 21428569 is about 277.7566016509.

The spelling of 21428569 in words is "twenty-one million, four hundred twenty-eight thousand, five hundred sixty-nine".