21004550243 has 4 divisors (see below), whose sum is σ = 22240112040. Its totient is φ = 19768988448.

The previous prime is 21004550221. The next prime is 21004550251. The reversal of 21004550243 is 34205540012.

It is a happy number.

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 21004550243 - 2¹⁸ = 21004288099 is a prime.

It is a super-2 number, since 2×21004550243² (a number of 21 digits) contains 22 as substring.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21004552243) 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, 617780873 + ... + 617780906.

It is an arithmetic number, because the mean of its divisors is an integer number (5560028010).

Almost surely, 2^21004550243 is an apocalyptic number.

21004550243 is a deficient number, since it is larger than the sum of its proper divisors (1235561797).

21004550243 is a wasteful number, since it uses less digits than its factorization.

21004550243 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1235561796.

The product of its (nonzero) digits is 4800, while the sum is 26.

The spelling of 21004550243 in words is "twenty-one billion, four million, five hundred fifty thousand, two hundred forty-three".