209726081 has 2 divisors, whose sum is σ = 209726082. Its totient is φ = 209726080.

The previous prime is 209726071. The next prime is 209726107. The reversal of 209726081 is 180627902.

It is a happy number.

It is a weak prime.

It can be written as a sum of positive squares in only one way, i.e., 168766081 + 40960000 = 12991^2 + 6400^2 .

It is a cyclic number.

It is not a de Polignac number, because 209726081 - 2¹⁴ = 209709697 is a prime.

It is a super-2 number, since 2×209726081² = 87970058103237122, which contains 22 as substring.

It is not a weakly prime, because it can be changed into another prime (209726051) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 104863040 + 104863041.

It is an arithmetic number, because the mean of its divisors is an integer number (104863041).

Almost surely, 2^209726081 is an apocalyptic number.

It is an amenable number.

209726081 is a deficient number, since it is larger than the sum of its proper divisors (1).

209726081 is an equidigital number, since it uses as much as digits as its factorization.

209726081 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 12096, while the sum is 35.

The square root of 209726081 is about 14481.9225588318. The cubic root of 209726081 is about 594.1336458193.

The spelling of 209726081 in words is "two hundred nine million, seven hundred twenty-six thousand, eighty-one".