261211109 has 2 divisors, whose sum is σ = 261211110. Its totient is φ = 261211108.

The previous prime is 261211087. The next prime is 261211117. The reversal of 261211109 is 901112162.

It is a happy number.

It is a strong prime.

It can be written as a sum of positive squares in only one way, i.e., 207994084 + 53217025 = 14422^2 + 7295^2 .

It is a cyclic number.

It is not a de Polignac number, because 261211109 - 2²⁰ = 260162533 is a prime.

It is a congruent number.

It is not a weakly prime, because it can be changed into another prime (261211199) by changing a digit.

It is a polite number, since it can be written as a sum of consecutive naturals, namely, 130605554 + 130605555.

It is an arithmetic number, because the mean of its divisors is an integer number (130605555).

Almost surely, 2^261211109 is an apocalyptic number.

It is an amenable number.

261211109 is a deficient number, since it is larger than the sum of its proper divisors (1).

261211109 is an equidigital number, since it uses as much as digits as its factorization.

261211109 is an evil number, because the sum of its binary digits is even.

The product of its (nonzero) digits is 216, while the sum is 23.

The square root of 261211109 is about 16162.0267602798. The cubic root of 261211109 is about 639.2399090019.

The spelling of 261211109 in words is "two hundred sixty-one million, two hundred eleven thousand, one hundred nine".