21497289 has 16 divisors (see below), whose sum is σ = 31350720. Its totient is φ = 12994560.

The previous prime is 21497269. The next prime is 21497293. The reversal of 21497289 is 98279412.

It is not a de Polignac number, because 21497289 - 2⁵ = 21497257 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21497289.

It is not an unprimeable number, because it can be changed into a prime (21497269) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 18477 + ... + 19605.

It is an arithmetic number, because the mean of its divisors is an integer number (1959420).

Almost surely, 2^21497289 is an apocalyptic number.

It is an amenable number.

21497289 is a deficient number, since it is larger than the sum of its proper divisors (9853431).

21497289 is a wasteful number, since it uses less digits than its factorization.

21497289 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1720.

The product of its digits is 72576, while the sum is 42.

The square root of 21497289 is about 4636.5169038838. The cubic root of 21497289 is about 278.0532004873.

The spelling of 21497289 in words is "twenty-one million, four hundred ninety-seven thousand, two hundred eighty-nine".