1281566666640 has 160 divisors (see below), whose sum is σ = 4279049873280. Its totient is φ = 315419148288.

The previous prime is 1281566666623. The next prime is 1281566666647. The reversal of 1281566666640 is 466666651821.

It is not an unprimeable number, because it can be changed into a prime (1281566666647) by changing a digit.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 26692576 + ... + 26740544.

It is an arithmetic number, because the mean of its divisors is an integer number (26744061708).

Almost surely, 2^{1281566666640} is an apocalyptic number.

1281566666640 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 1281566666640, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (2139524936640).

1281566666640 is an abundant number, since it is smaller than the sum of its proper divisors (2997483206640).

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

1281566666640 is a wasteful number, since it uses less digits than its factorization.

1281566666640 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 56561 (or 56555 counting only the distinct ones).

The product of its (nonzero) digits is 14929920, while the sum is 57.

The spelling of 1281566666640 in words is "one trillion, two hundred eighty-one billion, five hundred sixty-six million, six hundred sixty-six thousand, six hundred forty".