643325561 has 4 divisors (see below), whose sum is σ = 645421392. Its totient is φ = 641229732.

The previous prime is 643325497. The next prime is 643325563. The reversal of 643325561 is 165523346.

It is a semiprime because it is the product of two primes, and also a Blum integer, because the two primes are equal to 3 mod 4.

It is a cyclic number.

It is not a de Polignac number, because 643325561 - 2⁶ = 643325497 is a prime.

It is a Duffinian number.

It is not an unprimeable number, because it can be changed into a prime (643325563) 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, 1047455 + ... + 1048068.

It is an arithmetic number, because the mean of its divisors is an integer number (161355348).

Almost surely, 2^643325561 is an apocalyptic number.

It is an amenable number.

643325561 is a deficient number, since it is larger than the sum of its proper divisors (2095831).

643325561 is a wasteful number, since it uses less digits than its factorization.

643325561 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 2095830.

The product of its digits is 64800, while the sum is 35.

The square root of 643325561 is about 25363.8632901220. The cubic root of 643325561 is about 863.2639447552.

The spelling of 643325561 in words is "six hundred forty-three million, three hundred twenty-five thousand, five hundred sixty-one".