21489259 has 4 divisors (see below), whose sum is σ = 23442840. Its totient is φ = 19535680.

The previous prime is 21489257. The next prime is 21489271. The reversal of 21489259 is 95298412.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 21489259 - 2¹ = 21489257 is a prime.

It is a Smith number, since the sum of its digits (40) coincides with the sum of the digits of its prime factors. Since it is squarefree, it is also a hoax number.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21489257) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 976774 + ... + 976795.

It is an arithmetic number, because the mean of its divisors is an integer number (5860710).

Almost surely, 2^21489259 is an apocalyptic number.

21489259 is a deficient number, since it is larger than the sum of its proper divisors (1953581).

21489259 is a wasteful number, since it uses less digits than its factorization.

21489259 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1953580.

The product of its digits is 51840, while the sum is 40.

The square root of 21489259 is about 4635.6508712370. The cubic root of 21489259 is about 278.0185752645.

The spelling of 21489259 in words is "twenty-one million, four hundred eighty-nine thousand, two hundred fifty-nine".