1261279641600 has 1056 divisors, whose sum is σ = 5117720748480. Its totient is φ = 305764761600.

The previous prime is 1261279641553. The next prime is 1261279641617. The reversal of 1261279641600 is 61469721621.

1261279641600 is a `hidden beast` number, since 1 + 26 + 12 + 7 + 9 + 6 + 4 + 1 + 600 = 666.

It is a tau number, because it is divible by the number of its divisors (1056).

It is a Harshad number since it is a multiple of its sum of digits (45).

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, 114661785595 + ... + 114661785605.

Almost surely, 2^{1261279641600} is an apocalyptic number.

1261279641600 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1261279641600 is a droll number since its even prime factors and its odd prime factors have the same sum.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1261279641600, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2558860374240).

1261279641600 is an abundant number, since it is smaller than the sum of its proper divisors (3856441106880).

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

1261279641600 is an frugal number, since it uses more digits than its factorization.

1261279641600 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 84 (or 21 counting only the distinct ones).

The product of its (nonzero) digits is 217728, while the sum is 45.

The spelling of 1261279641600 in words is "one trillion, two hundred sixty-one billion, two hundred seventy-nine million, six hundred forty-one thousand, six hundred".