1261577120256 has 140 divisors (see below), whose sum is σ = 3779307583722. Its totient is φ = 420525582336.

The previous prime is 1261577120233. The next prime is 1261577120261. The reversal of 1261577120256 is 6520217751621.

1261577120256 is a `hidden beast` number, since 1 + 2 + 6 + 1 + 577 + 1 + 20 + 2 + 56 = 666.

It can be written as a sum of positive squares in only one way, i.e., 833233049856 + 428344070400 = 912816^2 + 654480^2 .

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (19) of ones.

It is a polite number, since it can be written in 13 ways as a sum of consecutive naturals, for example, 1316751 + ... + 2063246.

Almost surely, 2^{1261577120256} is an apocalyptic number.

1261577120256 is a gapful number since it is divisible by the number (16) formed by its first and last digit.

It is an amenable number.

1261577120256 is an abundant number, since it is smaller than the sum of its proper divisors (2517730463466).

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

1261577120256 is an frugal number, since it uses more digits than its factorization.

1261577120256 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 3380033 (or 3380002 counting only the distinct ones).

The product of its (nonzero) digits is 352800, while the sum is 45.

The spelling of 1261577120256 in words is "one trillion, two hundred sixty-one billion, five hundred seventy-seven million, one hundred twenty thousand, two hundred fifty-six".