21243340799 has 4 divisors (see below), whose sum is σ = 22166964336. Its totient is φ = 20319717264.

The previous prime is 21243340747. The next prime is 21243340819. The reversal of 21243340799 is 99704334212.

It is a semiprime because it is the product of two primes.

It is a de Polignac number, because none of the positive numbers 2^k-21243340799 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 (21243346799) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 461811734 + ... + 461811779.

It is an arithmetic number, because the mean of its divisors is an integer number (5541741084).

Almost surely, 2^21243340799 is an apocalyptic number.

21243340799 is a deficient number, since it is larger than the sum of its proper divisors (923623537).

21243340799 is an equidigital number, since it uses as much as digits as its factorization.

21243340799 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 923623536.

The product of its (nonzero) digits is 326592, while the sum is 44.

The spelling of 21243340799 in words is "twenty-one billion, two hundred forty-three million, three hundred forty thousand, seven hundred ninety-nine".