261211611 has 16 divisors (see below), whose sum is σ = 359997440. Its totient is φ = 168298560.

The previous prime is 261211609. The next prime is 261211651. The reversal of 261211611 is 116112162.

It is not a de Polignac number, because 261211611 - 2¹ = 261211609 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (261211651) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 94710 + ... + 97428.

It is an arithmetic number, because the mean of its divisors is an integer number (22499840).

Almost surely, 2^261211611 is an apocalyptic number.

261211611 is a deficient number, since it is larger than the sum of its proper divisors (98785829).

261211611 is a wasteful number, since it uses less digits than its factorization.

261211611 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3786.

The product of its digits is 144, while the sum is 21.

The square root of 261211611 is about 16162.0422905028. The cubic root of 261211611 is about 639.2403185024.

Adding to 261211611 its reverse (116112162), we get a palindrome (377323773).

The spelling of 261211611 in words is "two hundred sixty-one million, two hundred eleven thousand, six hundred eleven".