261553200750261 has 32 divisors (see below), whose sum is σ = 449078600908800. Its totient is φ = 147353915908080.

The previous prime is 261553200750251. The next prime is 261553200750269. The reversal of 261553200750261 is 162057002355162.

It is a happy number.

261553200750261 is a `hidden beast` number, since 2 + 6 + 1 + 5 + 532 + 0 + 0 + 7 + 50 + 2 + 61 = 666.

It is not a de Polignac number, because 261553200750261 - 2¹⁰ = 261553200749237 is a prime.

It is a Curzon number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261553200750269) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 9745615941 + ... + 9745642778.

It is an arithmetic number, because the mean of its divisors is an integer number (14033706278400).

Almost surely, 2^{261553200750261} is an apocalyptic number.

261553200750261 is a gapful number since it is divisible by the number (21) formed by its first and last digit.

It is an amenable number.

261553200750261 is a deficient number, since it is larger than the sum of its proper divisors (187525400158539).

261553200750261 is a wasteful number, since it uses less digits than its factorization.

261553200750261 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 19491258806 (or 19491258800 counting only the distinct ones).

The product of its (nonzero) digits is 756000, while the sum is 45.

The spelling of 261553200750261 in words is "two hundred sixty-one trillion, five hundred fifty-three billion, two hundred million, seven hundred fifty thousand, two hundred sixty-one".