2145805 has 4 divisors (see below), whose sum is σ = 2574972. Its totient is φ = 1716640.

The previous prime is 2145779. The next prime is 2145821. The reversal of 2145805 is 5085412.

It is a semiprime because it is the product of two primes.

It can be written as a sum of positive squares in 2 ways, for example, as 522729 + 1623076 = 723^2 + 1274^2 .

It is not a de Polignac number, because 2145805 - 2⁷ = 2145677 is a prime.

It is a Duffinian number.

2145805 is a lucky number.

It is a self number, because there is not a number n which added to its sum of digits gives 2145805.

It is a congruent number.

It is an unprimeable number.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 214576 + ... + 214585.

It is an arithmetic number, because the mean of its divisors is an integer number (643743).

2^2145805 is an apocalyptic number.

It is an amenable number.

2145805 is a deficient number, since it is larger than the sum of its proper divisors (429167).

2145805 is an equidigital number, since it uses as much as digits as its factorization.

2145805 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 429166.

The product of its (nonzero) digits is 1600, while the sum is 25.

The square root of 2145805 is about 1464.8566482765. The cubic root of 2145805 is about 128.9822902996.

The spelling of 2145805 in words is "two million, one hundred forty-five thousand, eight hundred five".