261499549409280 has 6048 divisors, whose sum is σ = 1263932578673856. Its totient is φ = 50524569206784.

The previous prime is 261499549409257. The next prime is 261499549409281. The reversal of 261499549409280 is 82904945994162.

261499549409280 is a `hidden beast` number, since 2 + 6 + 1 + 4 + 99 + 54 + 9 + 409 + 2 + 80 = 666.

It is a tau number, because it is divible by the number of its divisors (6048).

It is a Harshad number since it is a multiple of its sum of digits (72).

It is a junction number, because it is equal to n+sod(n) for n = 261499549409199 and 261499549409208.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261499549409281) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 431 ways as a sum of consecutive naturals, for example, 7067555389422 + ... + 7067555389458.

Almost surely, 2^{261499549409280} is an apocalyptic number.

261499549409280 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 261499549409280, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (631966289336928).

261499549409280 is an abundant number, since it is smaller than the sum of its proper divisors (1002433029264576).

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

261499549409280 is an frugal number, since it uses more digits than its factorization.

261499549409280 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 146 (or 84 counting only the distinct ones).

The product of its (nonzero) digits is 403107840, while the sum is 72.

The spelling of 261499549409280 in words is "two hundred sixty-one trillion, four hundred ninety-nine billion, five hundred forty-nine million, four hundred nine thousand, two hundred eighty".