261216506880 has 880 divisors, whose sum is σ = 1084347320640. Its totient is φ = 59630764032.

The previous prime is 261216506809. The next prime is 261216506897. The reversal of 261216506880 is 88605612162.

261216506880 is a `hidden beast` number, since 2 + 61 + 2 + 1 + 6 + 506 + 8 + 80 = 666.

It is a Harshad number since it is a multiple of its sum of digits (45).

It is a congruent number.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (17) of ones.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 331913847 + ... + 331914633.

Almost surely, 2^261216506880 is an apocalyptic number.

261216506880 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 261216506880, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (542173660320).

261216506880 is an abundant number, since it is smaller than the sum of its proper divisors (823130813760).

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

261216506880 is an frugal number, since it uses more digits than its factorization.

261216506880 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 849 (or 804 counting only the distinct ones).

The product of its (nonzero) digits is 276480, while the sum is 45.

The spelling of 261216506880 in words is "two hundred sixty-one billion, two hundred sixteen million, five hundred six thousand, eight hundred eighty".