1280785428 has 108 divisors (see below), whose sum is σ = 3534699168. Its totient is φ = 390836160.

The previous prime is 1280785427. The next prime is 1280785483. The reversal of 1280785428 is 8245870821.

It is a happy number.

It is a super-2 number, since 2×1280785428² = 3280822625154286368, which contains 22 as substring.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1280785427) by changing a digit.

It is a polite number, since it can be written in 35 ways as a sum of consecutive naturals, for example, 796201 + ... + 797807.

It is an arithmetic number, because the mean of its divisors is an integer number (32728696).

Almost surely, 2^1280785428 is an apocalyptic number.

1280785428 is a gapful number since it is divisible by the number (18) 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 1280785428, and also a Zumkeller number, because its divisors can be partitioned in two sets with the same sum (1767349584).

1280785428 is an abundant number, since it is smaller than the sum of its proper divisors (2253913740).

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

1280785428 is a wasteful number, since it uses less digits than its factorization.

1280785428 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1774 (or 1756 counting only the distinct ones).

The product of its (nonzero) digits is 286720, while the sum is 45.

The square root of 1280785428 is about 35788.0626466424. The cubic root of 1280785428 is about 1085.9890824376.

The spelling of 1280785428 in words is "one billion, two hundred eighty million, seven hundred eighty-five thousand, four hundred twenty-eight".