261221112 has 112 divisors (see below), whose sum is σ = 750759840. Its totient is φ = 85131648.

The previous prime is 261221111. The next prime is 261221113. The reversal of 261221112 is 211122162.

It is an interprime number because it is at equal distance from previous prime (261221111) and next prime (261221113).

It is a Harshad number since it is a multiple of its sum of digits (18).

It is a nude number because it is divisible by every one of its digits.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261221111) 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 27 ways as a sum of consecutive naturals, for example, 273628 + ... + 274580.

Almost surely, 2^261221112 is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261221112, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (375379920).

261221112 is an abundant number, since it is smaller than the sum of its proper divisors (489538728).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

261221112 is an equidigital number, since it uses as much as digits as its factorization.

261221112 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1024 (or 1005 counting only the distinct ones).

The product of its digits is 96, while the sum is 18.

The square root of 261221112 is about 16162.3362172676. The cubic root of 261221112 is about 639.2480687304.

Adding to 261221112 its reverse (211122162), we get a palindrome (472343274).

The spelling of 261221112 in words is "two hundred sixty-one million, two hundred twenty-one thousand, one hundred twelve".