21428259 has 8 divisors (see below), whose sum is σ = 28760832. Its totient is φ = 14190600.

The previous prime is 21428243. The next prime is 21428317. The reversal of 21428259 is 95282412.

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

It is not a de Polignac number, because 21428259 - 2⁴ = 21428243 is a prime.

It is not an unprimeable number, because it can be changed into a prime (21421259) 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, 23199 + ... + 24104.

It is an arithmetic number, because the mean of its divisors is an integer number (3595104).

Almost surely, 2^21428259 is an apocalyptic number.

21428259 is a deficient number, since it is larger than the sum of its proper divisors (7332573).

21428259 is a wasteful number, since it uses less digits than its factorization.

21428259 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 47457.

The product of its digits is 11520, while the sum is 33.

The square root of 21428259 is about 4629.0667525971. The cubic root of 21428259 is about 277.7552622402.

It can be divided in two parts, 2142 and 8259, that added together give a palindrome (10401).

The spelling of 21428259 in words is "twenty-one million, four hundred twenty-eight thousand, two hundred fifty-nine".