1205551 has 4 divisors (see below), whose sum is σ = 1209672. Its totient is φ = 1201432.

The previous prime is 1205549. The next prime is 1205557. The reversal of 1205551 is 1555021.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 1555021 = 13 ⋅119617.

It is a cyclic number.

It is not a de Polignac number, because 1205551 - 2¹ = 1205549 is a prime.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1205557) 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, 1585 + ... + 2218.

It is an arithmetic number, because the mean of its divisors is an integer number (302418).

2^1205551 is an apocalyptic number.

1205551 is a deficient number, since it is larger than the sum of its proper divisors (4121).

1205551 is an equidigital number, since it uses as much as digits as its factorization.

1205551 is an odious number, because the sum of its binary digits is odd.

The sum of its prime factors is 4120.

The product of its (nonzero) digits is 250, while the sum is 19.

The square root of 1205551 is about 1097.9758649442. The cubic root of 1205551 is about 106.4294609564.

It can be divided in two parts, 120 and 5551, that added together give a triangular number (5671 = T₁₀₆).

The spelling of 1205551 in words is "one million, two hundred five thousand, five hundred fifty-one".