21297799 has 4 divisors (see below), whose sum is σ = 21597840. Its totient is φ = 20997760.

The previous prime is 21297797. The next prime is 21297811. The reversal of 21297799 is 99779212.

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 21297799 - 2¹ = 21297797 is a prime.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (21297791) 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, 149914 + ... + 150055.

It is an arithmetic number, because the mean of its divisors is an integer number (5399460).

Almost surely, 2^21297799 is an apocalyptic number.

21297799 is a deficient number, since it is larger than the sum of its proper divisors (300041).

21297799 is an equidigital number, since it uses as much as digits as its factorization.

21297799 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 300040.

The product of its digits is 142884, while the sum is 46.

The square root of 21297799 is about 4614.9538459231. The cubic root of 21297799 is about 277.1904358465.

The spelling of 21297799 in words is "twenty-one million, two hundred ninety-seven thousand, seven hundred ninety-nine".