261366219544608 has 960 divisors, whose sum is σ = 856563756225408. Its totient is φ = 77812712570880.

The previous prime is 261366219544559. The next prime is 261366219544657. The reversal of 261366219544608 is 806445912663162.

It is a happy number.

261366219544608 is a `hidden beast` number, since 2 + 6 + 1 + 3 + 6 + 6 + 2 + 19 + 5 + 4 + 4 + 608 = 666.

It is an interprime number because it is at equal distance from previous prime (261366219544559) and next prime (261366219544657).

It is an unprimeable number.

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 159 ways as a sum of consecutive naturals, for example, 56855820966 + ... + 56855825562.

Almost surely, 2^{261366219544608} is an apocalyptic number.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261366219544608, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (428281878112704).

261366219544608 is an abundant number, since it is smaller than the sum of its proper divisors (595197536680800).

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

261366219544608 is a wasteful number, since it uses less digits than its factorization.

261366219544608 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5527 (or 5510 counting only the distinct ones).

The product of its (nonzero) digits is 89579520, while the sum is 63.

The spelling of 261366219544608 in words is "two hundred sixty-one trillion, three hundred sixty-six billion, two hundred nineteen million, five hundred forty-four thousand, six hundred eight".