209838095521 has 2 divisors, whose sum is σ = 209838095522. Its totient is φ = 209838095520.

The previous prime is 209838095479. The next prime is 209838095539. The reversal of 209838095521 is 125590838902.

209838095521 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 209361153600 + 476941921 = 457560^2 + 21839^2 .

It is a cyclic number.

It is not a de Polignac number, because 209838095521 - 2⁷ = 209838095393 is a prime.

It is a super-2 number, since 2×209838095521² (a number of 23 digits) contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (209838095321) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104919047760 + 104919047761.

It is an arithmetic number, because the mean of its divisors is an integer number (104919047761).

Almost surely, 2^209838095521 is an apocalyptic number.

It is an amenable number.

209838095521 is a deficient number, since it is larger than the sum of its proper divisors (1).

209838095521 is an equidigital number, since it uses as much as digits as its factorization.

209838095521 is an odious number, because the sum of its binary digits is odd.

The product of its (nonzero) digits is 1555200, while the sum is 52.

The spelling of 209838095521 in words is "two hundred nine billion, eight hundred thirty-eight million, ninety-five thousand, five hundred twenty-one".