209859531841 has 2 divisors, whose sum is σ = 209859531842. Its totient is φ = 209859531840.

The previous prime is 209859531839. The next prime is 209859531851. The reversal of 209859531841 is 148135958902.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 138535817616 + 71323714225 = 372204^2 + 267065^2 .

It is a cyclic number.

It is not a de Polignac number, because 209859531841 - 2¹ = 209859531839 is a prime.

Together with 209859531839, it forms a pair of twin primes.

It is not a weakly prime, because it can be changed into another prime (209859531851) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104929765920 + 104929765921.

It is an arithmetic number, because the mean of its divisors is an integer number (104929765921).

Almost surely, 2^209859531841 is an apocalyptic number.

It is an amenable number.

209859531841 is a deficient number, since it is larger than the sum of its proper divisors (1).

209859531841 is an equidigital number, since it uses as much as digits as its factorization.

209859531841 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 3110400, while the sum is 55.

The spelling of 209859531841 in words is "two hundred nine billion, eight hundred fifty-nine million, five hundred thirty-one thousand, eight hundred forty-one".