1261904661504 has 1056 divisors, whose sum is σ = 4173013544960. Its totient is φ = 365484441600.

The previous prime is 1261904661491. The next prime is 1261904661529. The reversal of 1261904661504 is 4051664091621.

1261904661504 is a `hidden beast` number, since 1 + 26 + 1 + 9 + 0 + 4 + 6 + 615 + 0 + 4 = 666.

It is a self number, because there is not a number n which added to its sum of digits gives 1261904661504.

It is an unprimeable number.

It is a polite number, since it can be written in 95 ways as a sum of consecutive naturals, for example, 12251501517 + ... + 12251501619.

Almost surely, 2^{1261904661504} 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 1261904661504, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2086506772480).

1261904661504 is an abundant number, since it is smaller than the sum of its proper divisors (2911108883456).

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

1261904661504 is a wasteful number, since it uses less digits than its factorization.

1261904661504 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 277 (or 256 counting only the distinct ones).

The product of its (nonzero) digits is 311040, while the sum is 45.

The spelling of 1261904661504 in words is "one trillion, two hundred sixty-one billion, nine hundred four million, six hundred sixty-one thousand, five hundred four".