1205811 has 6 divisors (see below), whose sum is σ = 1741740. Its totient is φ = 803868.

The previous prime is 1205779. The next prime is 1205819. The reversal of 1205811 is 1185021.

It is not a de Polignac number, because 1205811 - 2⁵ = 1205779 is a prime.

It is not an unprimeable number, because it can be changed into a prime (1205819) by changing a digit.

It is a polite number, since it can be written in 5 ways as a sum of consecutive naturals, for example, 66981 + ... + 66998.

It is an arithmetic number, because the mean of its divisors is an integer number (290290).

2^1205811 is an apocalyptic number.

1205811 is a deficient number, since it is larger than the sum of its proper divisors (535929).

1205811 is a wasteful number, since it uses less digits than its factorization.

1205811 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 133985 (or 133982 counting only the distinct ones).

The product of its (nonzero) digits is 80, while the sum is 18.

The square root of 1205811 is about 1098.0942582493. The cubic root of 1205811 is about 106.4371115855.

It can be divided in two parts, 1205 and 811, that added together give a triangular number (2016 = T₆₃).

The spelling of 1205811 in words is "one million, two hundred five thousand, eight hundred eleven".