1820845 has 16 divisors (see below), whose sum is σ = 2383920. Its totient is φ = 1327104.

The previous prime is 1820843. The next prime is 1820857. The reversal of 1820845 is 5480281.

It can be written as a sum of positive squares in 8 ways, for example, as 49284 + 1771561 = 222^2 + 1331^2 .

It is a 7-Lehmer number, since φ(1820845) divides (1820845-1)⁷.

It is a cyclic number.

It is not a de Polignac number, because 1820845 - 2¹ = 1820843 is a prime.

It is an Ulam number.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1820843) by changing a digit.

It is a polite number, since it can be written in 15 ways as a sum of consecutive naturals, for example, 6957 + ... + 7213.

It is an arithmetic number, because the mean of its divisors is an integer number (148995).

2^1820845 is an apocalyptic number.

It is an amenable number.

1820845 is a deficient number, since it is larger than the sum of its proper divisors (563075).

1820845 is a wasteful number, since it uses less digits than its factorization.

1820845 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 384.

The product of its (nonzero) digits is 2560, while the sum is 28.

The square root of 1820845 is about 1349.3868978169. The cubic root of 1820845 is about 122.1118073832. Note that the first 3 decimals are identical.

The spelling of 1820845 in words is "one million, eight hundred twenty thousand, eight hundred forty-five".