21297873 has 4 divisors (see below), whose sum is σ = 28397168. Its totient is φ = 14198580.

The previous prime is 21297869. The next prime is 21297907. The reversal of 21297873 is 37879212.

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 not a de Polignac number, because 21297873 - 2² = 21297869 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21297853) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 3549643 + ... + 3549648.

It is an arithmetic number, because the mean of its divisors is an integer number (7099292).

Almost surely, 2^21297873 is an apocalyptic number.

It is an amenable number.

21297873 is a deficient number, since it is larger than the sum of its proper divisors (7099295).

21297873 is an equidigital number, since it uses as much as digits as its factorization.

21297873 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 7099294.

The product of its digits is 42336, while the sum is 39.

The square root of 21297873 is about 4614.9618633311. The cubic root of 21297873 is about 277.1907568823.

The spelling of 21297873 in words is "twenty-one million, two hundred ninety-seven thousand, eight hundred seventy-three".