21084799 has 4 divisors (see below), whose sum is σ = 21381840. Its totient is φ = 20787760.

The previous prime is 21084797. The next prime is 21084803. The reversal of 21084799 is 99748012.

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 21084799 - 2¹ = 21084797 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 (21084797) 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, 148414 + ... + 148555.

It is an arithmetic number, because the mean of its divisors is an integer number (5345460).

Almost surely, 2^21084799 is an apocalyptic number.

21084799 is a deficient number, since it is larger than the sum of its proper divisors (297041).

21084799 is an equidigital number, since it uses as much as digits as its factorization.

21084799 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 297040.

The product of its (nonzero) digits is 36288, while the sum is 40.

The square root of 21084799 is about 4591.8187028671. The cubic root of 21084799 is about 276.2632744793.

It can be divided in two parts, 2 and 1084799, that added together give a palindrome (1084801).

The spelling of 21084799 in words is "twenty-one million, eighty-four thousand, seven hundred ninety-nine".