261261538776 has 320 divisors, whose sum is σ = 882037728000. Its totient is φ = 70580263680.

The previous prime is 261261538771. The next prime is 261261538781. The reversal of 261261538776 is 677835162162.

261261538776 is a `hidden beast` number, since 2 + 6 + 12 + 615 + 3 + 8 + 7 + 7 + 6 = 666.

It is an interprime number because it is at equal distance from previous prime (261261538771) and next prime (261261538781).

It is a Harshad number since it is a multiple of its sum of digits (54).

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (261261538771) by changing a digit.

It is a polite number, since it can be written in 79 ways as a sum of consecutive naturals, for example, 49208410 + ... + 49213718.

It is an arithmetic number, because the mean of its divisors is an integer number (2756367900).

Almost surely, 2^261261538776 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 261261538776, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (441018864000).

261261538776 is an abundant number, since it is smaller than the sum of its proper divisors (620776189224).

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

261261538776 is a wasteful number, since it uses less digits than its factorization.

261261538776 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 5924 (or 5911 counting only the distinct ones).

The product of its digits is 5080320, while the sum is 54.

The spelling of 261261538776 in words is "two hundred sixty-one billion, two hundred sixty-one million, five hundred thirty-eight thousand, seven hundred seventy-six".