261115811 has 4 divisors (see below), whose sum is σ = 284853624. Its totient is φ = 237378000.

The previous prime is 261115793. The next prime is 261115847. The reversal of 261115811 is 118511162.

It is a semiprime because it is the product of two primes.

It is a cyclic number.

It is not a de Polignac number, because 261115811 - 2¹⁸ = 260853667 is a prime.

It is not an unprimeable number, because it can be changed into a prime (261115871) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11868890 + ... + 11868911.

It is an arithmetic number, because the mean of its divisors is an integer number (71213406).

Almost surely, 2^261115811 is an apocalyptic number.

261115811 is a deficient number, since it is larger than the sum of its proper divisors (23737813).

261115811 is a wasteful number, since it uses less digits than its factorization.

261115811 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 23737812.

The product of its digits is 480, while the sum is 26.

The square root of 261115811 is about 16159.0782843577. The cubic root of 261115811 is about 639.1621612945.

Adding to 261115811 its reverse (118511162), we get a palindrome (379626973).

The spelling of 261115811 in words is "two hundred sixty-one million, one hundred fifteen thousand, eight hundred eleven".