1285645721680 has 80 divisors (see below), whose sum is σ = 3007146240144. Its totient is φ = 511159562240.

The previous prime is 1285645721669. The next prime is 1285645721707. The reversal of 1285645721680 is 861275465821.

It can be written as a sum of positive squares in 8 ways, for example, as 8329847824 + 1277315873856 = 91268^2 + 1130184^2 .

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

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 72803412 + ... + 72821068.

Almost surely, 2^{1285645721680} is an apocalyptic number.

1285645721680 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 1285645721680, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1503573120072).

1285645721680 is an abundant number, since it is smaller than the sum of its proper divisors (1721500518464).

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

1285645721680 is a wasteful number, since it uses less digits than its factorization.

1285645721680 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 23104 (or 23098 counting only the distinct ones).

The product of its (nonzero) digits is 6451200, while the sum is 55.

The spelling of 1285645721680 in words is "one trillion, two hundred eighty-five billion, six hundred forty-five million, seven hundred twenty-one thousand, six hundred eighty".