261566807040 has 880 divisors, whose sum is σ = 1168733896704. Its totient is φ = 54344908800.

The previous prime is 261566806951. The next prime is 261566807077. The reversal of 261566807040 is 40708665162.

261566807040 is a `hidden beast` number, since 2 + 6 + 1 + 566 + 80 + 7 + 0 + 4 + 0 = 666.

It is a tau number, because it is divible by the number of its divisors (880).

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, 31929345 + ... + 31937535.

Almost surely, 2^261566807040 is an apocalyptic number.

261566807040 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 261566807040, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (584366948352).

261566807040 is an abundant number, since it is smaller than the sum of its proper divisors (907167089664).

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

261566807040 is a wasteful number, since it uses less digits than its factorization.

261566807040 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 8246 (or 8219 counting only the distinct ones).

The product of its (nonzero) digits is 483840, while the sum is 45.

The spelling of 261566807040 in words is "two hundred sixty-one billion, five hundred sixty-six million, eight hundred seven thousand, forty".