261553772137122 has 96 divisors (see below), whose sum is σ = 614027846697408. Its totient is φ = 80142789500928.

The previous prime is 261553772137081. The next prime is 261553772137153. The reversal of 261553772137122 is 221731277355162.

261553772137122 is a `hidden beast` number, since 2 + 6 + 1 + 5 + 537 + 7 + 2 + 13 + 71 + 22 = 666.

It is an unprimeable number.

It is a polite number, since it can be written in 47 ways as a sum of consecutive naturals, for example, 212453713 + ... + 213681275.

It is an arithmetic number, because the mean of its divisors is an integer number (6396123403098).

Almost surely, 2^{261553772137122} is an apocalyptic number.

It is a practical number, because each smaller number is the sum of distinct divisors of 261553772137122, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (307013923348704).

261553772137122 is an abundant number, since it is smaller than the sum of its proper divisors (352474074560286).

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

261553772137122 is a wasteful number, since it uses less digits than its factorization.

261553772137122 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 1243824 (or 1243821 counting only the distinct ones).

The product of its digits is 7408800, while the sum is 54.

The spelling of 261553772137122 in words is "two hundred sixty-one trillion, five hundred fifty-three billion, seven hundred seventy-two million, one hundred thirty-seven thousand, one hundred twenty-two".