1820644388 has 12 divisors (see below), whose sum is σ = 3204545820. Its totient is φ = 905059872.

The previous prime is 1820644367. The next prime is 1820644403. The reversal of 1820644388 is 8834460281.

It can be written as a sum of positive squares in 2 ways, for example, as 1424156644 + 396487744 = 37738^2 + 19912^2 .

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, 1314803 + ... + 1316186.

It is an arithmetic number, because the mean of its divisors is an integer number (267045485).

Almost surely, 2^1820644388 is an apocalyptic number.

It is an amenable number.

1820644388 is a deficient number, since it is larger than the sum of its proper divisors (1383901432).

1820644388 is a wasteful number, since it uses less digits than its factorization.

1820644388 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2631166 (or 2631164 counting only the distinct ones).

The product of its (nonzero) digits is 294912, while the sum is 44.

The square root of 1820644388 is about 42669.0096908752. The cubic root of 1820644388 is about 1221.0732265341.

The spelling of 1820644388 in words is "one billion, eight hundred twenty million, six hundred forty-four thousand, three hundred eighty-eight".