1643200765 has 4 divisors (see below), whose sum is σ = 1971840924. Its totient is φ = 1314560608.

The previous prime is 1643200751. The next prime is 1643200771. The reversal of 1643200765 is 5670023461.

It is a happy number.

It is a semiprime because it is the product of two primes, and also an emirpimes, since its reverse is a distinct semiprime: 5670023461 = 16631 ⋅340931.

It can be written as a sum of positive squares in 2 ways, for example, as 571162201 + 1072038564 = 23899^2 + 32742^2 .

It is a cyclic number.

It is not a de Polignac number, because 1643200765 - 2⁵ = 1643200733 is a prime.

It is a Duffinian number.

It is a self number, because there is not a number n which added to its sum of digits gives 1643200765.

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, 164320072 + ... + 164320081.

It is an arithmetic number, because the mean of its divisors is an integer number (492960231).

Almost surely, 2^1643200765 is an apocalyptic number.

It is an amenable number.

1643200765 is a deficient number, since it is larger than the sum of its proper divisors (328640159).

1643200765 is an equidigital number, since it uses as much as digits as its factorization.

1643200765 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 328640158.

The product of its (nonzero) digits is 30240, while the sum is 34.

The square root of 1643200765 is about 40536.4128284682. The cubic root of 1643200765 is about 1180.0404000819.

The spelling of 1643200765 in words is "one billion, six hundred forty-three million, two hundred thousand, seven hundred sixty-five".