21504044213 has 2 divisors, whose sum is σ = 21504044214. Its totient is φ = 21504044212.

The previous prime is 21504044207. The next prime is 21504044251. The reversal of 21504044213 is 31244040512.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 21037181764 + 466862449 = 145042^2 + 21607^2 .

It is a cyclic number.

It is a de Polignac number, because none of the positive numbers 2^k-21504044213 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (27504044213) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10752022106 + 10752022107.

It is an arithmetic number, because the mean of its divisors is an integer number (10752022107).

Almost surely, 2^21504044213 is an apocalyptic number.

It is an amenable number.

21504044213 is a deficient number, since it is larger than the sum of its proper divisors (1).

21504044213 is an equidigital number, since it uses as much as digits as its factorization.

21504044213 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3840, while the sum is 26.

Adding to 21504044213 its reverse (31244040512), we get a palindrome (52748084725).

The spelling of 21504044213 in words is "twenty-one billion, five hundred four million, forty-four thousand, two hundred thirteen".