1281890 has 8 divisors (see below), whose sum is σ = 2307420. Its totient is φ = 512752.

The previous prime is 1281883. The next prime is 1281899. The reversal of 1281890 is 981821.

It can be written as a sum of positive squares in 2 ways, for example, as 1164241 + 117649 = 1079^2 + 343^2 .

It is a sphenic number, since it is the product of 3 distinct primes.

It is not an unprimeable number, because it can be changed into a prime (1281899) by changing a digit.

It is a pernicious number, because its binary representation contains a prime number (11) of ones.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 64085 + ... + 64104.

2^1281890 is an apocalyptic number.

1281890 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

1281890 is a deficient number, since it is larger than the sum of its proper divisors (1025530).

1281890 is a wasteful number, since it uses less digits than its factorization.

1281890 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 128196.

The product of its (nonzero) digits is 1152, while the sum is 29.

The square root of 1281890 is about 1132.2058116791. The cubic root of 1281890 is about 108.6301184796.

The spelling of 1281890 in words is "one million, two hundred eighty-one thousand, eight hundred ninety".