1281905 has 16 divisors (see below), whose sum is σ = 1638144. Its totient is φ = 960960.

The previous prime is 1281899. The next prime is 1281937. The reversal of 1281905 is 5091821.

It is a happy number.

It is not a de Polignac number, because 1281905 - 2⁸ = 1281649 is a prime.

It is a Duffinian number.

It is a Curzon 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, 8087 + ... + 8243.

It is an arithmetic number, because the mean of its divisors is an integer number (102384).

2^1281905 is an apocalyptic number.

It is an amenable number.

1281905 is a deficient number, since it is larger than the sum of its proper divisors (356239).

1281905 is a wasteful number, since it uses less digits than its factorization.

1281905 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 256.

The product of its (nonzero) digits is 720, while the sum is 26.

The square root of 1281905 is about 1132.2124358971. The cubic root of 1281905 is about 108.6305421887.

Multiplying 1281905 by its sum of digits (26), we get a triangular number (33329530 = T₈₁₆₄).

The spelling of 1281905 in words is "one million, two hundred eighty-one thousand, nine hundred five".