261143220 has 192 divisors, whose sum is σ = 844462080. Its totient is φ = 59761152.

The previous prime is 261143209. The next prime is 261143221. The reversal of 261143220 is 22341162.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261143221) by changing a digit.

It is a polite number, since it can be written in 63 ways as a sum of consecutive naturals, for example, 992809 + ... + 993071.

It is an arithmetic number, because the mean of its divisors is an integer number (4398240).

Almost surely, 2^261143220 is an apocalyptic number.

261143220 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261143220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (422231040).

261143220 is an abundant number, since it is smaller than the sum of its proper divisors (583318860).

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

261143220 is a wasteful number, since it uses less digits than its factorization.

261143220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 374 (or 372 counting only the distinct ones).

The product of its (nonzero) digits is 576, while the sum is 21.

The square root of 261143220 is about 16159.9263612184. The cubic root of 261143220 is about 639.1845245295.

Adding to 261143220 its reverse (22341162), we get a palindrome (283484382).

The spelling of 261143220 in words is "two hundred sixty-one million, one hundred forty-three thousand, two hundred twenty".