21356683108261 has 2 divisors, whose sum is σ = 21356683108262. Its totient is φ = 21356683108260.

The previous prime is 21356683108193. The next prime is 21356683108379. The reversal of 21356683108261 is 16280138665312.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 14207102331361 + 7149580776900 = 3769231^2 + 2673870^2 .

It is a cyclic number.

It is not a de Polignac number, because 21356683108261 - 2¹³ = 21356683100069 is a prime.

It is a super-2 number, since 2×21356683108261² (a number of 27 digits) contains 22 as substring.

It is a junction number, because it is equal to n+sod(n) for n = 21356683108199 and 21356683108208.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (21356683108961) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 10678341554130 + 10678341554131.

It is an arithmetic number, because the mean of its divisors is an integer number (10678341554131).

Almost surely, 2^{21356683108261} is an apocalyptic number.

It is an amenable number.

21356683108261 is a deficient number, since it is larger than the sum of its proper divisors (1).

21356683108261 is an equidigital number, since it uses as much as digits as its factorization.

21356683108261 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 2488320, while the sum is 52.

The spelling of 21356683108261 in words is "twenty-one trillion, three hundred fifty-six billion, six hundred eighty-three million, one hundred eight thousand, two hundred sixty-one".