261821280 has 192 divisors, whose sum is σ = 975421440. Its totient is φ = 57759744.

The previous prime is 261821279. The next prime is 261821299. The reversal of 261821280 is 82128162.

261821280 is digitally balanced in base 2, because in such base it contains all the possibile digits an equal number of times.

It is a Harshad number since it is a multiple of its sum of digits (30).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 96097 + ... + 98783.

It is an arithmetic number, because the mean of its divisors is an integer number (5080320).

Almost surely, 2^261821280 is an apocalyptic number.

261821280 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 261821280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (487710720).

261821280 is an abundant number, since it is smaller than the sum of its proper divisors (713600160).

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

261821280 is a wasteful number, since it uses less digits than its factorization.

261821280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2741 (or 2733 counting only the distinct ones).

The product of its (nonzero) digits is 3072, while the sum is 30.

The square root of 261821280 is about 16180.8924352151. The cubic root of 261821280 is about 639.7372619450.

The spelling of 261821280 in words is "two hundred sixty-one million, eight hundred twenty-one thousand, two hundred eighty".