261841821696 has 448 divisors, whose sum is σ = 954879878400. Its totient is φ = 69051875328.

The previous prime is 261841821653. The next prime is 261841821721. The reversal of 261841821696 is 696128148162.

261841821696 is a `hidden beast` number, since 2 + 6 + 1 + 8 + 418 + 216 + 9 + 6 = 666.

It is a tau number, because it is divible by the number of its divisors (448).

It is a super-3 number, since 3×261841821696³ (a number of 35 digits) contains 333 as substring. Note that it is a super-d number also for d = 2.

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a nude number because it is divisible by every one of its digits.

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, 20121240 + ... + 20134248.

It is an arithmetic number, because the mean of its divisors is an integer number (2131428300).

Almost surely, 2^261841821696 is an apocalyptic number.

261841821696 is a gapful number since it is divisible by the number (26) 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 261841821696, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (477439939200).

261841821696 is an abundant number, since it is smaller than the sum of its proper divisors (693038056704).

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

261841821696 is a wasteful number, since it uses less digits than its factorization.

261841821696 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 13064 (or 13034 counting only the distinct ones).

The product of its digits is 1990656, while the sum is 54.

The spelling of 261841821696 in words is "two hundred sixty-one billion, eight hundred forty-one million, eight hundred twenty-one thousand, six hundred ninety-six".