21297489 has 4 divisors (see below), whose sum is σ = 28396656. Its totient is φ = 14198324.

The previous prime is 21297487. The next prime is 21297509. The reversal of 21297489 is 98479212.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 21297489 - 2¹ = 21297487 is a prime.

It is a self number, because there is not a number n which added to its sum of digits gives 21297489.

It is not an unprimeable number, because it can be changed into a prime (21297487) 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, 3549579 + ... + 3549584.

It is an arithmetic number, because the mean of its divisors is an integer number (7099164).

Almost surely, 2^21297489 is an apocalyptic number.

It is an amenable number.

21297489 is a deficient number, since it is larger than the sum of its proper divisors (7099167).

21297489 is an equidigital number, since it uses as much as digits as its factorization.

21297489 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 7099166.

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

The square root of 21297489 is about 4614.9202593328. The cubic root of 21297489 is about 277.1890909587.

The spelling of 21297489 in words is "twenty-one million, two hundred ninety-seven thousand, four hundred eighty-nine".