261144520 has 192 divisors, whose sum is σ = 758706480. Its totient is φ = 80123904.

The previous prime is 261144503. The next prime is 261144529. The reversal of 261144520 is 25441162.

It is a happy number.

It can be written as a sum of positive squares in 8 ways, for example, as 75585636 + 185558884 = 8694^2 + 13622^2 .

It is not an unprimeable number, because it can be changed into a prime (261144529) by changing a digit.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 942622 + ... + 942898.

Almost surely, 2^261144520 is an apocalyptic number.

261144520 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 261144520, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (379353240).

261144520 is an abundant number, since it is smaller than the sum of its proper divisors (497561960).

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

261144520 is a wasteful number, since it uses less digits than its factorization.

261144520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 352 (or 341 counting only the distinct ones).

The product of its (nonzero) digits is 1920, while the sum is 25.

The square root of 261144520 is about 16159.9665841239. The cubic root of 261144520 is about 639.1855851716.

Adding to 261144520 its reverse (25441162), we get a palindrome (286585682).

The spelling of 261144520 in words is "two hundred sixty-one million, one hundred forty-four thousand, five hundred twenty".