21853636813 has 2 divisors, whose sum is σ = 21853636814. Its totient is φ = 21853636812.

The previous prime is 21853636759. The next prime is 21853636841. The reversal of 21853636813 is 31863635812.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 20598564484 + 1255072329 = 143522^2 + 35427^2 .

It is a cyclic number.

It is not a de Polignac number, because 21853636813 - 2²⁵ = 21820082381 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21853636213) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10926818406 + 10926818407.

It is an arithmetic number, because the mean of its divisors is an integer number (10926818407).

Almost surely, 2^21853636813 is an apocalyptic number.

It is an amenable number.

21853636813 is a deficient number, since it is larger than the sum of its proper divisors (1).

21853636813 is an equidigital number, since it uses as much as digits as its factorization.

21853636813 is an evil number, because the sum of its binary digits is even.

The product of its digits is 622080, while the sum is 46.

The spelling of 21853636813 in words is "twenty-one billion, eight hundred fifty-three million, six hundred thirty-six thousand, eight hundred thirteen".