1643204520 has 48 divisors (see below), whose sum is σ = 5340415860. Its totient is φ = 438187776.

The previous prime is 1643204471. The next prime is 1643204533. The reversal of 1643204520 is 254023461.

1643204520 is digitally balanced in base 4, because in such base it contains all the possibile digits an equal number of times.

It can be written as a sum of positive squares in 2 ways, for example, as 1607849604 + 35354916 = 40098^2 + 5946^2 .

It is an unprimeable number.

It is a polite number, since it can be written in 11 ways as a sum of consecutive naturals, for example, 2281869 + ... + 2282588.

Almost surely, 2^1643204520 is an apocalyptic number.

1643204520 is a gapful number since it is divisible by the number (10) formed by its first and last digit.

It is an amenable number.

1643204520 is an abundant number, since it is smaller than the sum of its proper divisors (3697211340).

It is a pseudoperfect number, because it is the sum of a subset of its proper divisors.

1643204520 is a wasteful number, since it uses less digits than its factorization.

1643204520 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 4564474 (or 4564467 counting only the distinct ones).

The product of its (nonzero) digits is 5760, while the sum is 27.

The square root of 1643204520 is about 40536.4591448242. The cubic root of 1643204520 is about 1180.0412989472.

Adding to 1643204520 its reverse (254023461), we get a palindrome (1897227981).

The spelling of 1643204520 in words is "one billion, six hundred forty-three million, two hundred four thousand, five hundred twenty".