1643330813 has 4 divisors (see below), whose sum is σ = 1665842268. Its totient is φ = 1620819360.

The previous prime is 1643330809. The next prime is 1643330831. The reversal of 1643330813 is 3180333461.

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 931348324 + 711982489 = 30518^2 + 26683^2 .

It is a cyclic number.

It is not a de Polignac number, because 1643330813 - 2² = 1643330809 is a prime.

It is a super-3 number, since 3×1643330813³ (a number of 29 digits) contains 333 as substring.

It is a Duffinian number.

It is a Curzon number.

It is a self number, because there is not a number n which added to its sum of digits gives 1643330813.

It is a congruent number.

It is not an unprimeable number, because it can be changed into a prime (1643330803) by changing a digit.

It is a polite number, since it can be written in 3 ways as a sum of consecutive naturals, for example, 11255618 + ... + 11255763.

It is an arithmetic number, because the mean of its divisors is an integer number (416460567).

Almost surely, 2^1643330813 is an apocalyptic number.

It is an amenable number.

1643330813 is a deficient number, since it is larger than the sum of its proper divisors (22511455).

1643330813 is an equidigital number, since it uses as much as digits as its factorization.

1643330813 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 22511454.

The product of its (nonzero) digits is 15552, while the sum is 32.

The square root of 1643330813 is about 40538.0168853880. The cubic root of 1643330813 is about 1180.0715299452.

The spelling of 1643330813 in words is "one billion, six hundred forty-three million, three hundred thirty thousand, eight hundred thirteen".