261638837784016 has 1920 divisors, whose sum is σ = 736702927994880. Its totient is φ = 87625359360000.

The previous prime is 261638837783977. The next prime is 261638837784041. The reversal of 261638837784016 is 610487738836162.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 383 ways as a sum of consecutive naturals, for example, 2060148328945 + ... + 2060148329071.

It is an arithmetic number, because the mean of its divisors is an integer number (383699441664).

Almost surely, 2^{261638837784016} 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 261638837784016, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (368351463997440).

261638837784016 is an abundant number, since it is smaller than the sum of its proper divisors (475064090210864).

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

261638837784016 is a wasteful number, since it uses less digits than its factorization.

261638837784016 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 425 (or 408 counting only the distinct ones).

The product of its (nonzero) digits is 390168576, while the sum is 70.

It can be divided in two parts, 2616388 and 37784016, that added together give a palindrome (40400404).

The spelling of 261638837784016 in words is "two hundred sixty-one trillion, six hundred thirty-eight billion, eight hundred thirty-seven million, seven hundred eighty-four thousand, sixteen".