261201556844240 has 20 divisors (see below), whose sum is σ = 607293619663044. Its totient is φ = 104480622737664.

The previous prime is 261201556844231. The next prime is 261201556844243. The reversal of 261201556844240 is 42448655102162.

It can be written as a sum of positive squares in 2 ways, for example, as 49666523312704 + 211535033531536 = 7047448^2 + 14544244^2 .

It is a tau number, because it is divible by the number of its divisors (20).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261201556844243) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 1632509730197 + ... + 1632509730356.

Almost surely, 2^{261201556844240} is an apocalyptic number.

261201556844240 is a gapful number since it is divisible by the number (20) formed by its first and last digit.

It is an amenable number.

261201556844240 is an abundant number, since it is smaller than the sum of its proper divisors (346092062818804).

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

261201556844240 is a wasteful number, since it uses less digits than its factorization.

261201556844240 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3265019460566 (or 3265019460560 counting only the distinct ones).

The product of its (nonzero) digits is 3686400, while the sum is 50.

The spelling of 261201556844240 in words is "two hundred sixty-one trillion, two hundred one billion, five hundred fifty-six million, eight hundred forty-four thousand, two hundred forty".