261863280 has 400 divisors, whose sum is σ = 1088930304. Its totient is φ = 57024000.

The previous prime is 261863279. The next prime is 261863297. The reversal of 261863280 is 82368162.

261863280 is a `hidden beast` number, since 2 + 6 + 18 + 632 + 8 + 0 = 666.

It is a Harshad number since it is a multiple of its sum of digits (36).

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 1043155 + ... + 1043405.

Almost surely, 2^261863280 is an apocalyptic number.

261863280 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 261863280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (544465152).

261863280 is an abundant number, since it is smaller than the sum of its proper divisors (827067024).

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

261863280 is a wasteful number, since it uses less digits than its factorization.

261863280 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 306 (or 291 counting only the distinct ones).

The product of its (nonzero) digits is 27648, while the sum is 36.

The square root of 261863280 is about 16182.1902102280. The cubic root of 261863280 is about 639.7714678843.

The spelling of 261863280 in words is "two hundred sixty-one million, eight hundred sixty-three thousand, two hundred eighty".