643675649 has 4 divisors (see below), whose sum is σ = 646910400. Its totient is φ = 640440900.

The previous prime is 643675621. The next prime is 643675691. The reversal of 643675649 is 946576346.

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 643675649 - 2¹⁶ = 643610113 is a prime.

It is a super-2 number, since 2×643675649² = 828636682231142402, which contains 22 as substring.

It is a Duffinian number.

It is a junction number, because it is equal to n+sod(n) for n = 643675597 and 643675606.

It is not an unprimeable number, because it can be changed into a prime (643675609) 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, 1617077 + ... + 1617474.

It is an arithmetic number, because the mean of its divisors is an integer number (161727600).

Almost surely, 2^643675649 is an apocalyptic number.

It is an amenable number.

643675649 is a deficient number, since it is larger than the sum of its proper divisors (3234751).

643675649 is a wasteful number, since it uses less digits than its factorization.

643675649 is an evil number, because the sum of its binary digits is even.

The sum of its prime factors is 3234750.

The product of its digits is 3265920, while the sum is 50.

The square root of 643675649 is about 25370.7636660783. The cubic root of 643675649 is about 863.4205080683.

The spelling of 643675649 in words is "six hundred forty-three million, six hundred seventy-five thousand, six hundred forty-nine".