1281815 has 4 divisors (see below), whose sum is σ = 1538184. Its totient is φ = 1025448.

The previous prime is 1281809. The next prime is 1281821. The reversal of 1281815 is 5181821.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5181821 = 17 ⋅304813.

It is an interprime number because it is at equal distance from previous prime (1281809) and next prime (1281821).

It is a cyclic number.

It is not a de Polignac number, because 1281815 - 2⁴ = 1281799 is a prime.

It is a Duffinian number.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 128177 + ... + 128186.

It is an arithmetic number, because the mean of its divisors is an integer number (384546).

2^1281815 is an apocalyptic number.

1281815 is a deficient number, since it is larger than the sum of its proper divisors (256369).

1281815 is an equidigital number, since it uses as much as digits as its factorization.

1281815 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 256368.

The product of its digits is 640, while the sum is 26.

The square root of 1281815 is about 1132.1726900080. The cubic root of 1281815 is about 108.6279998845.

The spelling of 1281815 in words is "one million, two hundred eighty-one thousand, eight hundred fifteen".