261428816220 has 1152 divisors, whose sum is σ = 998181273600. Its totient is φ = 50197708800.

The previous prime is 261428816191. The next prime is 261428816227. The reversal of 261428816220 is 22618824162.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261428816227) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (23) of ones.

It is a polite number, since it can be written in 383 ways as a sum of consecutive naturals, for example, 1460496091 + ... + 1460496269.

It is an arithmetic number, because the mean of its divisors is an integer number (866476800).

Almost surely, 2^261428816220 is an apocalyptic number.

261428816220 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 261428816220, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (499090636800).

261428816220 is an abundant number, since it is smaller than the sum of its proper divisors (736752457380).

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

261428816220 is a wasteful number, since it uses less digits than its factorization.

261428816220 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 299 (or 280 counting only the distinct ones).

The product of its (nonzero) digits is 147456, while the sum is 42.

The spelling of 261428816220 in words is "two hundred sixty-one billion, four hundred twenty-eight million, eight hundred sixteen thousand, two hundred twenty".