1261281680 has 80 divisors (see below), whose sum is σ = 3114443520. Its totient is φ = 473389056.

The previous prime is 1261281661. The next prime is 1261281713. The reversal of 1261281680 is 861821621.

It is a tau number, because it is divible by the number of its divisors (80).

It is a self number, because there is not a number n which added to its sum of digits gives 1261281680.

It is an unprimeable number.

It is a pernicious number, because its binary representation contains a prime number (13) of ones.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 514217 + ... + 516663.

It is an arithmetic number, because the mean of its divisors is an integer number (38930544).

Almost surely, 2^1261281680 is an apocalyptic number.

1261281680 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

It is a practical number, because each smaller number is the sum of distinct divisors of 1261281680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1557221760).

1261281680 is an abundant number, since it is smaller than the sum of its proper divisors (1853161840).

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

1261281680 is a wasteful number, since it uses less digits than its factorization.

1261281680 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 2856 (or 2850 counting only the distinct ones).

The product of its (nonzero) digits is 9216, while the sum is 35.

The square root of 1261281680 is about 35514.5277316199. The cubic root of 1261281680 is about 1080.4483963414.

The spelling of 1261281680 in words is "one billion, two hundred sixty-one million, two hundred eighty-one thousand, six hundred eighty".