1280781 has 12 divisors (see below), whose sum is σ = 1869660. Its totient is φ = 844800.

The previous prime is 1280767. The next prime is 1280789. The reversal of 1280781 is 1870821.

It can be written as a sum of positive squares in 2 ways, for example, as 585225 + 695556 = 765^2 + 834^2 .

It is not a de Polignac number, because 1280781 - 2¹⁰ = 1279757 is a prime.

It is a super-2 number, since 2×1280781² = 3280799939922, which contains 22 as substring.

It is an Ulam number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1280789) by changing a digit.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 205 + ... + 1613.

It is an arithmetic number, because the mean of its divisors is an integer number (155805).

2^1280781 is an apocalyptic number.

It is an amenable number.

1280781 is a deficient number, since it is larger than the sum of its proper divisors (588879).

1280781 is a wasteful number, since it uses less digits than its factorization.

1280781 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 1516 (or 1513 counting only the distinct ones).

The product of its (nonzero) digits is 896, while the sum is 27.

The square root of 1280781 is about 1131.7159537623. The cubic root of 1280781 is about 108.5987830923.

The spelling of 1280781 in words is "one million, two hundred eighty thousand, seven hundred eighty-one".