261223111 has 4 divisors (see below), whose sum is σ = 261300424. Its totient is φ = 261145800.

The previous prime is 261223103. The next prime is 261223147. The reversal of 261223111 is 111322162.

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 261223111 - 2³ = 261223103 is a prime.

It is a super-4 number, since 4×261223111⁴ (a number of 35 digits) contains 4444 as substring.

It is a Duffinian number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261223181) 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 3 ways as a sum of consecutive naturals, for example, 33345 + ... + 40426.

It is an arithmetic number, because the mean of its divisors is an integer number (65325106).

Almost surely, 2^261223111 is an apocalyptic number.

261223111 is a deficient number, since it is larger than the sum of its proper divisors (77313).

261223111 is an equidigital number, since it uses as much as digits as its factorization.

261223111 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 77312.

The product of its digits is 144, while the sum is 19.

The square root of 261223111 is about 16162.3980584565. The cubic root of 261223111 is about 639.2496993460.

Adding to 261223111 its reverse (111322162), we get a palindrome (372545273).

The spelling of 261223111 in words is "two hundred sixty-one million, two hundred twenty-three thousand, one hundred eleven".