21043402313 has 4 divisors (see below), whose sum is σ = 21043739028. Its totient is φ = 21043065600.

The previous prime is 21043402283. The next prime is 21043402339. The reversal of 21043402313 is 31320434012.

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

It can be written as a sum of positive squares in 2 ways, for example, as 8677295104 + 12366107209 = 93152^2 + 111203^2 .

It is a cyclic number.

It is not a de Polignac number, because 21043402313 - 2¹⁰ = 21043401289 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (21043402363) 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, 43988 + ... + 209813.

It is an arithmetic number, because the mean of its divisors is an integer number (5260934757).

Almost surely, 2^21043402313 is an apocalyptic number.

It is an amenable number.

21043402313 is a deficient number, since it is larger than the sum of its proper divisors (336715).

21043402313 is an equidigital number, since it uses as much as digits as its factorization.

21043402313 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 336714.

The product of its (nonzero) digits is 1728, while the sum is 23.

Adding to 21043402313 its reverse (31320434012), we get a palindrome (52363836325).

The spelling of 21043402313 in words is "twenty-one billion, forty-three million, four hundred two thousand, three hundred thirteen".