1820644385 has 32 divisors (see below), whose sum is σ = 2568775680. Its totient is φ = 1212613632.

The previous prime is 1820644367. The next prime is 1820644403. The reversal of 1820644385 is 5834460281.

It is an interprime number because it is at equal distance from previous prime (1820644367) and next prime (1820644403).

It is a cyclic number.

It is not a de Polignac number, because 1820644385 - 2⁸ = 1820644129 is a prime.

It is an unprimeable number.

It is a polite number, since it can be written in 31 ways as a sum of consecutive naturals, for example, 1264496 + ... + 1265934.

It is an arithmetic number, because the mean of its divisors is an integer number (80274240).

Almost surely, 2^1820644385 is an apocalyptic number.

It is an amenable number.

1820644385 is a deficient number, since it is larger than the sum of its proper divisors (748131295).

1820644385 is a wasteful number, since it uses less digits than its factorization.

1820644385 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2465.

The product of its (nonzero) digits is 184320, while the sum is 41.

The square root of 1820644385 is about 42669.0096557209. The cubic root of 1820644385 is about 1221.0732258635.

The spelling of 1820644385 in words is "one billion, eight hundred twenty million, six hundred forty-four thousand, three hundred eighty-five".