261531315045 has 384 divisors, whose sum is σ = 643081420800. Its totient is φ = 94693017600.

The previous prime is 261531314999. The next prime is 261531315047. The reversal of 261531315045 is 540513135162.

261531315045 is a `hidden beast` number, since 2 + 6 + 1 + 531 + 31 + 50 + 45 = 666.

It is not a de Polignac number, because 261531315045 - 2⁶ = 261531314981 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261531315047) by changing a digit.

It is a polite number, since it can be written in 383 ways as a sum of consecutive naturals, for example, 368873151 + ... + 368873859.

It is an arithmetic number, because the mean of its divisors is an integer number (1674691200).

Almost surely, 2^261531315045 is an apocalyptic number.

It is an amenable number.

261531315045 is an abundant number, since it is smaller than the sum of its proper divisors (381550105755).

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

261531315045 is a wasteful number, since it uses less digits than its factorization.

261531315045 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1201 (or 1198 counting only the distinct ones).

The product of its (nonzero) digits is 54000, while the sum is 36.

The spelling of 261531315045 in words is "two hundred sixty-one billion, five hundred thirty-one million, three hundred fifteen thousand, forty-five".